Merge res_fax and res_fax_spandsp.

git-svn-id: http://svn.digium.com/svn/asterisk/trunk@250190 f38db490-d61c-443f-a65b-d21fe96a405b

3 files changed, 2664 insertions, 0 deletions

diff --git a/res/res_fax.c b/res/res_fax.c
new file mode 100644
index 000000000..36ca2601b
--- /dev/null
+++ b/res/res_fax.c
@@ -0,0 +1,1891 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2008-2009, Digium, Inc.
+ *
+ * Dwayne M. Hubbard <dhubbard@digium.com>
+ * Kevin P. Fleming <kpfleming@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Generic FAX Resource for FAX technology resource modules
+ *
+ * \author Dwayne M. Hubbard <dhubbard@digium.com>
+ * \author Kevin P. Fleming <kpfleming@digium.com>
+ * 
+ * A generic FAX resource module that provides SendFAX and ReceiveFAX applications.
+ * This module requires FAX technology modules, like res_fax_spandsp, to register with it
+ * so it can use the technology modules to perform the actual FAX transmissions.
+ * \ingroup applications
+ */
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#include "asterisk/io.h"
+#include "asterisk/file.h"
+#include "asterisk/logger.h"
+#include "asterisk/module.h"
+#include "asterisk/app.h"
+#include "asterisk/lock.h"
+#include "asterisk/options.h"
+#include "asterisk/strings.h"
+#include "asterisk/cli.h"
+#include "asterisk/utils.h"
+#include "asterisk/config.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/file.h"
+#include "asterisk/channel.h"
+#include "asterisk/pbx.h"
+#include "asterisk/manager.h"
+#include "asterisk/dsp.h"
+#include "asterisk/res_fax.h"
+
+static const char app_receivefax[] = "ReceiveFAX";
+static const char synopsis_receivefax[] = "Receive a FAX and save as a TIFF/F file.";
+static const char descrip_receivefax[] = "ReceiveFAX(filename[,options]):\n"
+ " The ReceiveFAX() application receives a FAX as a TIFF/F file with specified filename.\n"
+ " The application arguments are:\n"
+ "    'd' - enables FAX debugging\n"
+ "    'f' - allow audio fallback FAX transfer on T.38 capable channels\n"
+ "    's' - send progress Manager events (overrides statusevents setting in res_fax.conf)\n"
+ "\n"
+ " Use the FAXOPT function to specify session arguments prior to calling ReceiveFAX()\n"
+ " and use FAXOPT after ReceiveFAX completes to query result status for the session.\n"
+ " The ReceiveFAX() is provided by res_fax, which is a FAX technology agnostic module\n"
+ " that utilizes FAX technology resource modules to complete a FAX transmission.\n";
+
+static const char app_sendfax[] = "SendFAX";
+static const char synopsis_sendfax[] = "Sends a specified TIFF/F file as a FAX.";
+static const char descrip_sendfax[] = "SendFAX(filename[,options]):\n"
+ " The SendFAX() application sends the specified TIFF/F file as a FAX.\n"
+ " The application arguments are:\n"
+ "    'd' - enables FAX debugging\n"
+ "    'f' - allow audio fallback FAX transfer on T.38 capable channels\n"
+ "    's' - send progress Manager events (overrides statusevents setting in res_fax.conf)\n"
+ "\n"
+ " Use the FAXOPT function to specify session arguments prior to calling SendFAX()\n"
+ " and use FAXOPT after SendFAX completes to query result status for the session.\n"
+ " The SendFAX() application is provided by res_fax, which is a FAX technology agnostic module\n"
+ " that utilizes FAX technology resource modules to complete a FAX transmission.\n";
+
+struct debug_info_history {
+	unsigned int consec_frames;
+	unsigned int consec_ms;
+	unsigned char silence;
+};
+
+struct ast_fax_debug_info {
+	struct timeval base_tv;
+	struct debug_info_history c2s, s2c;
+	struct ast_dsp *dsp;
+};
+
+/*! \brief maximum buckets for res_fax ao2 containers */
+#define FAX_MAXBUCKETS 10
+
+#define RES_FAX_TIMEOUT 10000
+
+/*! \brief The faxregistry is used to manage information and statistics for all FAX sessions. */
+static struct {
+	/*! The number of active FAX sessions */
+	int active_sessions;
+	/*! active sessions are astobj2 objects */
+	struct ao2_container *container;
+	/*! Total number of Tx FAX attempts */
+	int fax_tx_attempts;
+	/*! Total number of Rx FAX attempts */
+	int fax_rx_attempts;
+	/*! Number of successful FAX transmissions */
+	int fax_complete;
+	/*! Number of failed FAX transmissions */
+	int fax_failures;
+	/*! the next unique session name */
+	int nextsessionname;
+} faxregistry;
+
+/*! \brief registered FAX technology modules are put into this list */
+struct fax_module {
+	const struct ast_fax_tech *tech;
+	AST_RWLIST_ENTRY(fax_module) list;
+};
+static AST_RWLIST_HEAD_STATIC(faxmodules, fax_module);
+
+#define RES_FAX_MINRATE 2400
+#define RES_FAX_MAXRATE 14400
+#define RES_FAX_STATUSEVENTS 0
+#define RES_FAX_MODEM (AST_FAX_MODEM_V17 | AST_FAX_MODEM_V27 | AST_FAX_MODEM_V29)
+
+static struct {
+	enum ast_fax_modems modems;
+	uint32_t statusevents:1;
+	unsigned int minrate;	
+	unsigned int maxrate;
+} general_options;
+
+static const char *config = "res_fax.conf";
+
+static int global_fax_debug = 0;
+
+enum {
+	OPT_CALLEDMODE = (1 << 0),
+	OPT_CALLERMODE = (1 << 1),
+	OPT_DEBUG      = (1 << 2),
+	OPT_STATUS     = (1 << 3),
+	OPT_ALLOWAUDIO = (1 << 5),
+};
+
+AST_APP_OPTIONS(fax_exec_options, BEGIN_OPTIONS
+	AST_APP_OPTION('a', OPT_CALLEDMODE),
+	AST_APP_OPTION('c', OPT_CALLERMODE),
+	AST_APP_OPTION('d', OPT_DEBUG),
+	AST_APP_OPTION('f', OPT_ALLOWAUDIO),
+	AST_APP_OPTION('s', OPT_STATUS),
+END_OPTIONS);
+
+struct manager_event_info {
+	char context[AST_MAX_CONTEXT];
+	char exten[AST_MAX_EXTENSION];
+	char cid[128];
+};
+
+static void debug_check_frame_for_silence(struct ast_fax_session *s, unsigned int c2s, struct ast_frame *frame)
+{	
+	struct debug_info_history *history = c2s ? &s->debug_info->c2s : &s->debug_info->s2c;
+	int dspsilence;
+	unsigned int last_consec_frames, last_consec_ms;
+	unsigned char wassil;
+	struct timeval diff;
+
+	diff = ast_tvsub(ast_tvnow(), s->debug_info->base_tv);
+
+	ast_dsp_reset(s->debug_info->dsp);
+	ast_dsp_silence(s->debug_info->dsp, frame, &dspsilence);
+
+	wassil = history->silence;
+	history->silence = (dspsilence != 0) ? 1 : 0;
+	if (history->silence != wassil) {
+		last_consec_frames = history->consec_frames;
+		last_consec_ms = history->consec_ms;
+		history->consec_frames = 0;
+		history->consec_ms = 0;
+
+		if ((last_consec_frames != 0)) {
+			ast_verb(6, "Channel '%s' fax session '%d', [ %.3ld.%.6ld ], %s sent %d frames (%d ms) of %s.\n",
+				 s->channame, s->id, (long) diff.tv_sec, (long int) diff.tv_usec,
+				 (c2s) ? "channel" : "stack", last_consec_frames, last_consec_ms,
+				 (wassil) ? "silence" : "energy");
+		}
+	}
+
+	history->consec_frames++;
+	history->consec_ms += (frame->samples / 8);
+}
+
+static void destroy_callback(void *data) 
+{
+	if (data) {
+		ao2_ref(data, -1);
+	}
+}
+
+static const struct ast_datastore_info fax_datastore = {
+	.type = "res_fax",
+	.destroy = destroy_callback,
+};
+
+/*! \brief returns a reference counted pointer to a fax datastore, if it exists */
+static struct ast_fax_session_details *find_details(struct ast_channel *chan)
+{
+	struct ast_fax_session_details *details;
+	struct ast_datastore *datastore;
+
+	ast_channel_lock(chan);	
+	if (!(datastore = ast_channel_datastore_find(chan, &fax_datastore, NULL))) {
+		ast_channel_unlock(chan);	
+		return NULL;
+	}
+	if (!(details = datastore->data)) {
+		ast_log(LOG_WARNING, "Huh?  channel '%s' has a FAX datastore without data!\n", chan->name);
+		ast_channel_unlock(chan);
+		return NULL;
+	}
+	ao2_ref(details, 1);	
+	ast_channel_unlock(chan);	
+
+	return details;
+}
+
+/*! \brief destroy a FAX session details structure */
+static void destroy_session_details(void *details)
+{
+	struct ast_fax_session_details *d = details;
+	struct ast_fax_document *doc;
+	
+	while ((doc = AST_LIST_REMOVE_HEAD(&d->documents, next))) {
+		ast_free(doc);
+	}
+	ast_string_field_free_memory(d);	
+}
+
+/*! \brief create a FAX session details structure */
+static struct ast_fax_session_details *session_details_new(void)
+{
+	struct ast_fax_session_details *d;
+
+	if (!(d = ao2_alloc(sizeof(*d), destroy_session_details))) {
+		return NULL;
+	}
+	
+	if (ast_string_field_init(d, 512)) {
+		ao2_ref(d, -1);
+		return NULL;
+	}
+
+	AST_LIST_HEAD_INIT_NOLOCK(&d->documents);
+
+	/* These options need to be set to the configured default and may be overridden by
+ 	 * SendFAX, ReceiveFAX, or FAXOPT */
+	d->option.ecm = AST_FAX_OPTFLAG_DEFAULT;
+	d->option.statusevents = general_options.statusevents;
+	d->modems = general_options.modems;
+	d->minrate = general_options.minrate;
+	d->maxrate = general_options.maxrate;
+
+	return d;
+}
+
+/*! \brief returns a reference counted details structure from the channel's fax datastore.  If the datastore
+ * does not exist it will be created */	
+static struct ast_fax_session_details *find_or_create_details(struct ast_channel *chan)
+{
+	struct ast_fax_session_details *details;
+	struct ast_datastore *datastore;
+
+	if ((details = find_details(chan))) {
+		return details;
+	}
+	/* channel does not have one so we must create one */
+	if (!(details = session_details_new())) {
+		ast_log(LOG_WARNING, "channel '%s' can't get a FAX details structure for the datastore!\n", chan->name);
+		return NULL;
+	}
+	if (!(datastore = ast_datastore_alloc(&fax_datastore, NULL))) {
+		ao2_ref(details, -1);
+		ast_log(LOG_WARNING, "channel '%s' can't get a datastore!\n", chan->name);
+		return NULL;
+	}
+	/* add the datastore to the channel and increment the refcount */
+	datastore->data = details;
+	ao2_ref(details, 1);
+	ast_channel_lock(chan);
+	ast_channel_datastore_add(chan, datastore);
+	ast_channel_unlock(chan);
+	return details;
+}
+
+unsigned int ast_fax_maxrate(void)
+{
+	return general_options.maxrate;
+}
+
+unsigned int ast_fax_minrate(void)
+{
+	return general_options.minrate;
+}
+
+static int update_modem_bits(enum ast_fax_modems *bits, const char *value)
+{		
+	char *m[5], *tok, *v = (char *)value;
+	int i = 0, j;
+
+	if (!(tok = strchr(v, ','))) {
+		m[i++] = v;
+		m[i] = NULL;
+	} else {
+		tok = strtok(v, ", ");
+		while (tok && (i < 5)) {
+			m[i++] = tok;
+			tok = strtok(NULL, ", ");
+		}
+		m[i] = NULL;
+	}
+
+	*bits = 0;
+	for (j = 0; j < i; j++) {
+		if (!strcasecmp(m[j], "v17")) {
+			*bits |= AST_FAX_MODEM_V17;
+		} else if (!strcasecmp(m[j], "v27")) {
+			*bits |= AST_FAX_MODEM_V27;
+		} else if (!strcasecmp(m[j], "v29")) {
+			*bits |= AST_FAX_MODEM_V29;
+		} else if (!strcasecmp(m[j], "v34")) {
+			*bits |= AST_FAX_MODEM_V34;
+		} else {
+			ast_log(LOG_WARNING, "ignoring invalid modem setting: '%s', valid options {v17 | v27 | v29 | v34}\n", m[j]);
+		}
+	}
+	return 0;
+}
+
+static int ast_fax_modem_to_str(enum ast_fax_modems bits, char *tbuf, size_t bufsize)
+{
+	int count = 0;
+
+	if (bits & AST_FAX_MODEM_V17) {
+		strcat(tbuf, "V17");
+		count++;
+	}
+	if (bits & AST_FAX_MODEM_V27) {
+		if (count) {
+			strcat(tbuf, ",");
+		}
+		strcat(tbuf, "V27");
+		count++;
+	}
+	if (bits & AST_FAX_MODEM_V29) {
+		if (count) {
+			strcat(tbuf, ",");
+		}
+		strcat(tbuf, "V29");
+		count++;
+	}
+	if (bits & AST_FAX_MODEM_V34) {
+		if (count) {
+			strcat(tbuf, ",");
+		}
+		strcat(tbuf, "V34");
+		count++;
+	}
+
+	return 0;
+}
+
+/*! \brief register a FAX technology module */
+int ast_fax_tech_register(struct ast_fax_tech *tech)
+{
+	struct fax_module *fax;
+
+	if (!(fax = ast_calloc(1, sizeof(*fax)))) {
+		return -1;
+	}
+	fax->tech = tech;
+	AST_RWLIST_WRLOCK(&faxmodules);
+	AST_RWLIST_INSERT_TAIL(&faxmodules, fax, list);
+	AST_RWLIST_UNLOCK(&faxmodules);
+	ast_module_ref(ast_module_info->self);
+
+	ast_verb(3, "Registered handler for '%s' (%s)\n", fax->tech->type, fax->tech->description);
+
+	return 0;
+}
+
+/*! \brief unregister a FAX technology module */
+void ast_fax_tech_unregister(struct ast_fax_tech *tech)
+{
+	struct fax_module *fax;
+
+	ast_verb(3, "Unregistering FAX module type '%s'\n", tech->type);
+
+	AST_RWLIST_WRLOCK(&faxmodules);
+	AST_RWLIST_TRAVERSE_SAFE_BEGIN(&faxmodules, fax, list) {
+		if (fax->tech != tech) {
+			continue;
+		}
+		AST_RWLIST_REMOVE_CURRENT(list);
+		ast_module_unref(ast_module_info->self);
+		ast_free(fax);
+		ast_verb(4, "Unregistered FAX module type '%s'\n", tech->type);
+		break;	
+	}
+	AST_RWLIST_TRAVERSE_SAFE_END;
+	AST_RWLIST_UNLOCK(&faxmodules);
+}
+
+/*! \brief convert a ast_fax_state to a string */
+const char *ast_fax_state_to_str(enum ast_fax_state state)
+{
+	switch (state) {
+	case AST_FAX_STATE_UNINITIALIZED:
+		return "Uninitialized";
+	case AST_FAX_STATE_INITIALIZED:
+		return "Initialized";
+	case AST_FAX_STATE_OPEN:
+		return "Open";
+	case AST_FAX_STATE_ACTIVE:
+		return "Active";
+	case AST_FAX_STATE_COMPLETE:
+		return "Complete";
+	default:
+		ast_log(LOG_WARNING, "unhandled FAX state: %d\n", state);
+		return "Unknown";
+	}
+}
+
+/*! \brief convert a rate string to a rate */
+static int fax_rate_str_to_int(const char *ratestr)
+{
+	int rate;
+
+	if (sscanf(ratestr, "%d", &rate) != 1) {
+		ast_log(LOG_ERROR, "failed to sscanf '%s' to rate\n", ratestr);
+		return -1;
+	}
+	switch (rate) {
+	case 2400:
+	case 4800:
+	case 7200:
+	case 9600:
+	case 12000:
+	case 14400:
+	case 28800:
+	case 33600:
+		return rate;
+	default:
+		ast_log(LOG_WARNING, "ignoring invalid rate '%s'.  Valid options are {2400 | 4800 | 7200 | 9600 | 12000 | 14400 | 28800 | 33600}\n", ratestr);
+		return -1;
+	}
+}
+
+/*! \brief destroy a FAX session structure */
+static void destroy_session(void *session)
+{
+	struct ast_fax_session *s = session;
+
+	if (s->tech) {
+		if (s->tech_pvt) {
+			s->tech->destroy_session(s);
+		}
+		ast_module_unref(s->tech->module);
+	}
+
+	if (s->details) {
+		ao2_ref(s->details, -1);
+	}
+	
+	if (s->debug_info) {
+		ast_dsp_free(s->debug_info->dsp);
+		ast_free(s->debug_info);
+	}
+
+	if (s->smoother) {
+		ast_smoother_free(s->smoother);
+	}
+
+	ast_atomic_fetchadd_int(&faxregistry.active_sessions, -1);
+
+	ast_free(s->channame);
+}
+
+/*! \brief create a FAX session */
+static struct ast_fax_session *fax_session_new(struct ast_fax_session_details *details, struct ast_channel *chan)
+{
+	struct ast_fax_session *s;
+	struct fax_module *faxmod;
+
+	if (!(s = ao2_alloc(sizeof(*s), destroy_session))) {
+		return NULL;
+	}
+
+	ast_atomic_fetchadd_int(&faxregistry.active_sessions, 1);
+
+	if (details->option.debug && (details->caps & AST_FAX_TECH_AUDIO)) {
+		if (!(s->debug_info = ast_calloc(1, sizeof(*(s->debug_info))))) {
+			ao2_ref(s, -1);
+			return NULL;
+		}
+		if (!(s->debug_info->dsp = ast_dsp_new())) {
+			ast_free(s->debug_info);
+			s->debug_info = NULL;
+			ao2_ref(s, -1);
+			return NULL;
+		}
+		ast_dsp_set_threshold(s->debug_info->dsp, 128);
+	}	
+
+	if (!(s->channame = ast_strdup(chan->name))) {
+		ao2_ref(s, -1);
+		return NULL;
+	}
+	s->chan = chan;
+	s->details = details;
+	ao2_ref(s->details, 1);
+	s->state = AST_FAX_STATE_UNINITIALIZED;
+
+	details->id = s->id = ast_atomic_fetchadd_int(&faxregistry.nextsessionname, 1);
+
+	/* locate a FAX technology module that can handle said requirements */
+	AST_RWLIST_RDLOCK(&faxmodules);
+	AST_RWLIST_TRAVERSE(&faxmodules, faxmod, list) {
+		if ((faxmod->tech->caps & details->caps) != details->caps) {
+			continue;
+		}
+		ast_debug(4, "Requesting a new FAX session from '%s'.\n", faxmod->tech->description);
+		ast_module_ref(faxmod->tech->module);
+		s->tech = faxmod->tech;
+		break;
+	}
+	AST_RWLIST_UNLOCK(&faxmodules);
+
+	if (!faxmod) {
+		ast_log(LOG_ERROR, "Could not locate a FAX technology module with capabilities (0x%X)\n", details->caps);
+		ao2_ref(s, -1);
+		return NULL;
+	}
+	if (!(s->tech_pvt = s->tech->new_session(s, NULL))) {
+		ast_log(LOG_ERROR, "FAX session failed to initialize.\n");
+		ao2_ref(s, -1);
+		ast_module_unref(faxmod->tech->module);
+		return NULL;
+	}
+	/* link the session to the session container */
+	if (!(ao2_link(faxregistry.container, s))) {
+		ast_log(LOG_ERROR, "failed to add FAX session '%d' to container.\n", s->id);
+		ao2_ref(s, -1);
+		ast_module_unref(faxmod->tech->module);
+		return NULL;
+	}
+	ast_debug(4, "channel '%s' using FAX session '%d'\n", s->channame, s->id);
+
+	return s;
+}
+
+static void get_manager_event_info(struct ast_channel *chan, struct manager_event_info *info)
+{
+	pbx_substitute_variables_helper(chan, "${CONTEXT}", info->context, sizeof(info->context));
+	pbx_substitute_variables_helper(chan, "${EXTEN}", info->exten, sizeof(info->exten));
+	pbx_substitute_variables_helper(chan, "${CALLERID(num)}", info->cid, sizeof(info->cid));
+}
+
+/*! \brief send a FAX status manager event */
+static int report_fax_status(struct ast_channel *chan, struct ast_fax_session_details *details, const char *status)
+{
+	ast_channel_lock(chan);
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", status);
+	if (details->option.statusevents) {
+		struct manager_event_info info;
+
+		get_manager_event_info(chan, &info);
+		manager_event(EVENT_FLAG_CALL,
+			      (details->caps & AST_FAX_TECH_RECEIVE) ? "ReceiveFAXStatus" : "SendFAXStatus",
+			      "Status: %s\r\n"
+			      "Channel: %s\r\n"
+			      "Context: %s\r\n"
+			      "Exten: %s\r\n"
+			      "CallerID: %s\r\n"
+			      "LocalStationID: %s\r\n"
+			      "FileName: %s\r\n",
+			      status,
+			      chan->name,
+			      info.context,
+			      info.exten,
+			      info.cid,
+			      details->localstationid,
+			      AST_LIST_FIRST(&details->documents)->filename);
+	}
+	ast_channel_unlock(chan);
+
+	return 0;
+}
+
+#define GENERIC_FAX_EXEC_ERROR(fax, chan, reason)	\
+	do {	\
+		ast_log(LOG_ERROR, "channel '%s' FAX session '%d' failure, reason: '%s'\n", chan->name, fax->id, reason); \
+		pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", reason); \
+		if (ast_strlen_zero(fax->details->result)) ast_string_field_set(fax->details, result, "FAILED"); \
+		res = ms = -1; \
+	} while (0)
+
+static void t38_parameters_ast_to_fax(struct ast_fax_t38_parameters *dst, const struct ast_control_t38_parameters *src)
+{
+	dst->version = src->version;
+	dst->max_ifp = src->max_ifp;
+	dst->rate = src->rate;
+	dst->rate_management = src->rate_management;
+	dst->fill_bit_removal = src->fill_bit_removal;
+	dst->transcoding_mmr = src->transcoding_mmr;
+	dst->transcoding_jbig = src->transcoding_jbig;
+}
+
+static void t38_parameters_fax_to_ast(struct ast_control_t38_parameters *dst, const struct ast_fax_t38_parameters *src)
+{
+	dst->version = src->version;
+	dst->max_ifp = src->max_ifp;
+	dst->rate = src->rate;
+	dst->rate_management = src->rate_management;
+	dst->fill_bit_removal = src->fill_bit_removal;
+	dst->transcoding_mmr = src->transcoding_mmr;
+	dst->transcoding_jbig = src->transcoding_jbig;
+}
+
+/*! \brief this is the generic FAX session handling function */
+static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_details *details)
+{
+	int ms;
+	int timeout = RES_FAX_TIMEOUT;
+	int res = 0, chancount;
+	unsigned int expected_frametype = -1;
+	union ast_frame_subclass expected_framesubclass = { .integer = -1 };
+	char tbuf[10];
+	unsigned int t38negotiated = 0;
+	enum ast_t38_state t38_state;
+	struct ast_control_t38_parameters t38_parameters;
+	int send_cng = -1;
+	unsigned int disable_t38 = 0;
+	const char *tempvar;
+	struct ast_fax_session *fax = NULL;
+	struct ast_frame *frame = NULL;
+	struct ast_channel *c = chan;
+	unsigned int orig_write_format = 0, orig_read_format = 0;
+	unsigned int request_t38 = 0;
+
+	details->our_t38_parameters.version = 0;
+	details->our_t38_parameters.max_ifp = 400;
+	details->our_t38_parameters.rate = AST_T38_RATE_14400;
+	details->our_t38_parameters.rate_management = AST_T38_RATE_MANAGEMENT_TRANSFERRED_TCF;
+
+	chancount = 1;
+
+	/* generate 3 seconds of CED if we are in receive mode */
+	if (details->caps & AST_FAX_TECH_RECEIVE) {
+		ms = 3000;
+		if (ast_tonepair_start(chan, 2100, 0, ms, 0)) {
+			ast_log(LOG_ERROR, "error generating CED tone on %s\n", chan->name);
+			return -1;
+		}
+
+		do {
+			ms = ast_waitfor(chan, ms);
+			if (ms < 0) {
+				ast_log(LOG_ERROR, "error while generating CED tone on %s\n", chan->name);
+				ast_tonepair_stop(chan);
+				return -1;
+			}
+
+			if (ms == 0) { /* all done, nothing happened */
+				break;
+			}
+
+			if (!(frame = ast_read(chan))) {
+				ast_log(LOG_ERROR, "error reading frame while generating CED tone on %s\n", chan->name);
+				ast_tonepair_stop(chan);
+				return -1;
+			}
+
+			if ((frame->frametype == AST_FRAME_CONTROL) &&
+					(frame->subclass.integer == AST_CONTROL_T38_PARAMETERS) &&
+					(frame->datalen == sizeof(t38_parameters))) {
+				struct ast_control_t38_parameters *parameters = frame->data.ptr;
+
+				switch (parameters->request_response) {
+				case AST_T38_REQUEST_NEGOTIATE:
+					/* the other end has requested a switch to T.38, so reply that we are willing, if we can
+					 * do T.38 as well
+					 */
+					t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+					t38_parameters.request_response = (details->caps & AST_FAX_TECH_T38) ? AST_T38_NEGOTIATED : AST_T38_REFUSED;
+					ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters));
+					break;
+				case AST_T38_NEGOTIATED:
+					ast_log(LOG_NOTICE, "Negotiated T.38 for receive on %s\n", chan->name);
+					t38_parameters_ast_to_fax(&details->their_t38_parameters, parameters);
+					details->caps &= ~AST_FAX_TECH_AUDIO;
+					report_fax_status(chan, details, "T.38 Negotiated");
+					t38negotiated = 1;
+					ms = 0;
+					break;
+				default:
+					break;
+				}
+			}
+			ast_frfree(frame);
+		} while (ms > 0);
+		ast_tonepair_stop(chan);
+	}
+
+	switch ((t38_state = ast_channel_get_t38_state(chan))) {
+	case T38_STATE_UNKNOWN:
+		if (details->caps & AST_FAX_TECH_SEND) {
+			if (details->option.allow_audio) {
+				details->caps |= AST_FAX_TECH_AUDIO;
+			} else {
+				/* we are going to send CNG to attempt to stimulate the receiver
+				 * into switching to T.38, since audio mode is not allowed
+				 */
+				send_cng = 0;
+			}
+		} else {
+			/* we *always* request a switch to T.38 if allowed; if audio is also
+			 * allowed, then we will allow the switch to happen later if needed
+			 */
+			if (details->option.allow_audio) {
+				details->caps |= AST_FAX_TECH_AUDIO;
+			}
+			request_t38 = 1;
+		}
+		details->caps |= AST_FAX_TECH_T38;
+		break;
+	case T38_STATE_UNAVAILABLE:
+		details->caps |= AST_FAX_TECH_AUDIO;
+		break;
+	default:
+		ast_log(LOG_ERROR, "channel '%s' is in an unsupported T.38 negotiation state, cannot continue.\n", chan->name);
+		return -1;
+	}
+
+	if (request_t38) {
+		/* wait up to five seconds for negotiation to complete */
+		timeout = 5000;
+
+		/* set parameters based on the session's parameters */
+		t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+		t38_parameters.request_response = AST_T38_REQUEST_NEGOTIATE;
+		if ((ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters)) != 0)) {
+			res = -1;
+			goto t38done;
+		}
+
+		ast_log(LOG_NOTICE, "Negotiating T.38 for %s on %s\n", (details->caps & AST_FAX_TECH_SEND) ? "send" : "receive", chan->name);
+	} else if (!details->option.allow_audio) {
+		/* wait up to sixty seconds for negotiation to complete */
+		timeout = 60000;
+
+		ast_log(LOG_NOTICE, "Waiting for T.38 negotiation for %s on %s\n", (details->caps & AST_FAX_TECH_SEND) ? "send" : "receive", chan->name);
+	}
+
+	if (request_t38 || !details->option.allow_audio) {
+		struct ast_silence_generator *silence_gen = NULL;
+
+		if (send_cng != -1) {
+			silence_gen = ast_channel_start_silence_generator(chan);
+		}
+
+		while (timeout > 0) {
+			if (send_cng > 3000) {
+				ast_channel_stop_silence_generator(chan, silence_gen);
+				silence_gen = NULL;
+				ast_tonepair_start(chan, 1100, 0, 500, 0);
+				send_cng = 0;
+			} else if (!chan->generator && (send_cng != -1)) {
+				/* The CNG tone is done so restart silence generation. */
+				silence_gen = ast_channel_start_silence_generator(chan);
+			}
+			/* this timeout *MUST* be 500ms, in order to keep the spacing
+			 * of CNG tones correct when this loop is sending them
+			 */
+			ms = ast_waitfor(chan, 500);
+			if (ms < 0) {
+				ast_log(LOG_WARNING, "something bad happened while channel '%s' was polling.\n", chan->name);
+				res = -1;
+				break;
+			}
+			if (send_cng != -1) {
+				send_cng += 500 - ms;
+			}
+			if (!ms) {
+				/* nothing happened */
+				if (timeout > 0) {
+					timeout -= 500;
+					continue;
+				} else {
+					ast_log(LOG_WARNING, "channel '%s' timed-out during the T.38 negotiation.\n", chan->name);
+					res = -1;
+					break;
+				}
+			}
+			if (!(frame = ast_read(chan))) {
+				if (silence_gen) {
+					ast_channel_stop_silence_generator(chan, silence_gen);
+					silence_gen = NULL;
+				}
+				return -1;
+			}
+			if ((frame->frametype == AST_FRAME_CONTROL) &&
+			    (frame->subclass.integer == AST_CONTROL_T38_PARAMETERS) &&
+			    (frame->datalen == sizeof(t38_parameters))) {
+				struct ast_control_t38_parameters *parameters = frame->data.ptr;
+				int stop = 1;
+				
+				switch (parameters->request_response) {
+				case AST_T38_REQUEST_NEGOTIATE:
+					t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+					t38_parameters.request_response = AST_T38_NEGOTIATED;
+					ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters));
+					stop = 0;
+					break;
+				case AST_T38_NEGOTIATED:
+					ast_log(LOG_NOTICE, "Negotiated T.38 for %s on %s\n", (details->caps & AST_FAX_TECH_SEND) ? "send" : "receive", chan->name);
+					t38_parameters_ast_to_fax(&details->their_t38_parameters, parameters);
+					details->caps &= ~AST_FAX_TECH_AUDIO;
+					t38negotiated = 1;
+					disable_t38 = 1;
+					break;
+				case AST_T38_REFUSED:
+					ast_log(LOG_WARNING, "channel '%s' refused to negotiate T.38\n", chan->name);
+					res = -1;
+					break;
+				default:
+					ast_log(LOG_ERROR, "channel '%s' failed to negotiate T.38\n", chan->name);
+					res = -1;
+					break;
+				}
+				if (stop) {
+					ast_frfree(frame);
+					break;
+				}
+			}
+			ast_frfree(frame);
+		}
+
+		if (silence_gen) {
+			ast_channel_stop_silence_generator(chan, silence_gen);
+			silence_gen = NULL;
+		}
+	}
+
+t38done:
+	/* if any failures occurred during T.38 negotiation, handle them here */
+	if (res) {
+		/* if audio is allowed, then drop the T.38 session requirement
+		 * and proceed, otherwise the request has failed
+		 */
+		if (details->option.allow_audio) {
+			details->caps &= ~AST_FAX_TECH_T38;
+			res = 0;
+		} else {
+			ast_log(LOG_WARNING, "Audio FAX not allowed on channel '%s' and T.38 negotiation failed; aborting.\n", chan->name);
+			return -1;
+		}
+	}
+
+	/* create the FAX session */
+	if (!(fax = fax_session_new(details, chan))) {
+		ast_log(LOG_ERROR, "Can't create a FAX session, FAX attempt failed.\n");
+		report_fax_status(chan, details, "No Available Resource");
+		chancount = -1;
+		goto disable_t38;
+	}
+
+	ast_channel_lock(chan);
+	/* update session details */	
+	if (ast_strlen_zero(details->headerinfo) && (tempvar = pbx_builtin_getvar_helper(chan, "LOCALHEADERINFO"))) {
+		ast_string_field_set(details, headerinfo, tempvar);
+	}
+	if (ast_strlen_zero(details->localstationid)) {
+		tempvar = pbx_builtin_getvar_helper(chan, "LOCALSTATIONID");
+		ast_string_field_set(details, localstationid, tempvar ? tempvar : "unknown");
+	}
+	ast_channel_unlock(chan);
+
+	report_fax_status(chan, details, "Allocating Resources");
+
+	if (details->caps & AST_FAX_TECH_AUDIO) {
+		expected_frametype = AST_FRAME_VOICE;;
+		expected_framesubclass.codec = AST_FORMAT_SLINEAR;
+		orig_write_format = chan->writeformat;
+		if (ast_set_write_format(chan, AST_FORMAT_SLINEAR) < 0) {
+			ast_log(LOG_ERROR, "channel '%s' failed to set write format to signed linear'.\n", chan->name);
+ 			ao2_lock(faxregistry.container);
+ 			ao2_unlink(faxregistry.container, fax);
+ 			ao2_unlock(faxregistry.container);
+ 			ao2_ref(fax, -1);
+			ast_channel_unlock(chan);
+			return -1;
+		}
+		orig_read_format = chan->readformat;
+		if (ast_set_read_format(chan, AST_FORMAT_SLINEAR) < 0) {
+			ast_log(LOG_ERROR, "channel '%s' failed to set read format to signed linear.\n", chan->name);
+ 			ao2_lock(faxregistry.container);
+ 			ao2_unlink(faxregistry.container, fax);
+ 			ao2_unlock(faxregistry.container);
+ 			ao2_ref(fax, -1);
+			ast_channel_unlock(chan);
+			return -1;
+		}
+		if (fax->smoother) {
+			ast_smoother_free(fax->smoother);
+			fax->smoother = NULL;
+		}
+		if (!(fax->smoother = ast_smoother_new(320))) {
+			ast_log(LOG_WARNING, "Channel '%s' FAX session '%d' failed to obtain a smoother.\n", chan->name, fax->id);
+		}
+	} else {
+		expected_frametype = AST_FRAME_MODEM;
+		expected_framesubclass.codec = AST_MODEM_T38;
+	}
+
+	if (fax->debug_info) {
+		fax->debug_info->base_tv = ast_tvnow();
+	}
+	if (fax->tech->start_session(fax) < 0) {
+		GENERIC_FAX_EXEC_ERROR(fax, chan, "failed to start FAX session");
+	}
+
+	pbx_builtin_setvar_helper(chan, "FAXSTATUS", NULL);
+	pbx_builtin_setvar_helper(chan, "FAXERROR", NULL);
+	report_fax_status(chan, details, "FAX Transmission In Progress");
+
+	ast_debug(5, "channel %s will wait on FAX fd %d\n", chan->name, fax->fd);
+
+	/* handle frames for the session */
+	ms = 1000;
+	while ((ms > -1) && (timeout > 0)) {
+		struct ast_channel *ready_chan;
+		int ofd, exception;
+
+		ms = 1000;
+		errno = 0;
+		ready_chan = ast_waitfor_nandfds(&c, chancount, &fax->fd, 1, &exception, &ofd, &ms);
+		if (ready_chan) {
+			if (!(frame = ast_read(chan))) {
+				/* the channel is probably gone, so lets stop polling on it and let the
+ 				 * FAX session complete before we exit the application.  if needed,
+ 				 * send the FAX stack silence so the modems can finish their session without
+ 				 * any problems */
+				ast_log(LOG_NOTICE, "Channel '%s' did not return a frame; probably hung up.\n", chan->name);
+				c = NULL;
+				chancount = 0;
+				timeout -= (1000 - ms);
+				fax->tech->cancel_session(fax);
+				if (fax->tech->generate_silence) {
+					fax->tech->generate_silence(fax);
+				}
+				continue;
+			}
+
+			if ((frame->frametype == AST_FRAME_CONTROL) &&
+			    (frame->subclass.integer == AST_CONTROL_T38_PARAMETERS) &&
+			    (frame->datalen == sizeof(t38_parameters))) {
+				unsigned int was_t38 = t38negotiated;
+				struct ast_control_t38_parameters *parameters = frame->data.ptr;
+				
+				switch (parameters->request_response) {
+				case AST_T38_REQUEST_NEGOTIATE:
+					/* the other end has requested a switch to T.38, so reply that we are willing, if we can
+					 * do T.38 as well
+					 */
+					t38_parameters_fax_to_ast(&t38_parameters, &details->our_t38_parameters);
+					t38_parameters.request_response = (details->caps & AST_FAX_TECH_T38) ? AST_T38_NEGOTIATED : AST_T38_REFUSED;
+					ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters));
+					break;
+				case AST_T38_NEGOTIATED:
+					t38_parameters_ast_to_fax(&details->their_t38_parameters, parameters);
+					t38negotiated = 1;
+					break;
+				default:
+					break;
+				}
+				if (t38negotiated && !was_t38) {
+					fax->tech->switch_to_t38(fax);
+					details->caps &= ~AST_FAX_TECH_AUDIO;
+					expected_frametype = AST_FRAME_MODEM;
+					expected_framesubclass.codec = AST_MODEM_T38;
+					if (fax->smoother) {
+						ast_smoother_free(fax->smoother);
+						fax->smoother = NULL;
+					}
+					
+					report_fax_status(chan, details, "T.38 Negotiated");
+					
+					ast_verb(3, "Channel '%s' switched to T.38 FAX session '%d'.\n", chan->name, fax->id);
+				}
+			} else if ((frame->frametype == expected_frametype) &&
+				   (!memcmp(&frame->subclass, &expected_framesubclass, sizeof(frame->subclass)))) {
+				struct ast_frame *f;
+				
+				if (fax->smoother) {
+					/* push the frame into a smoother */
+					if (ast_smoother_feed(fax->smoother, frame) < 0) {
+						GENERIC_FAX_EXEC_ERROR(fax, chan, "Failed to feed the smoother");
+					}
+					while ((f = ast_smoother_read(fax->smoother)) && (f->data.ptr)) {
+						if (fax->debug_info) {
+							debug_check_frame_for_silence(fax, 1, f);
+						}
+						/* write the frame to the FAX stack */
+						fax->tech->write(fax, f);
+						fax->frames_received++;
+						if (f != frame) {
+							ast_frfree(f);
+						}
+					}
+				} else {
+					/* write the frame to the FAX stack */
+					fax->tech->write(fax, frame);
+					fax->frames_received++;
+				}
+				timeout = RES_FAX_TIMEOUT;
+			}
+			ast_frfree(frame);
+		} else if (ofd == fax->fd) {
+			/* read a frame from the FAX stack and send it out the channel.
+ 			 * the FAX stack will return a NULL if the FAX session has already completed */
+			if (!(frame = fax->tech->read(fax))) {
+				break;
+			}
+
+			if (fax->debug_info && (frame->frametype == AST_FRAME_VOICE)) {
+				debug_check_frame_for_silence(fax, 0, frame);
+			}
+
+			ast_write(chan, frame);
+			fax->frames_sent++;
+			ast_frfree(frame);
+			timeout = RES_FAX_TIMEOUT;
+		} else {
+			if (ms && (ofd < 0)) {
+				if ((errno == 0) || (errno == EINTR)) {
+					timeout -= (1000 - ms);
+					continue;
+				} else {
+					ast_log(LOG_WARNING, "something bad happened while channel '%s' was polling.\n", chan->name);
+					res = ms;
+					break;
+				}
+			} else {
+				/* nothing happened */
+				if (timeout > 0) {
+					timeout -= 1000;
+					continue;
+				} else {
+					ast_log(LOG_WARNING, "channel '%s' timed-out during the FAX transmission.\n", chan->name);
+					GENERIC_FAX_EXEC_ERROR(fax, chan, "fax session timed-out");
+					break;
+				}
+			}
+		}
+	}
+	ast_debug(3, "channel '%s' - event loop stopped { timeout: %d, ms: %d, res: %d }\n", chan->name, timeout, ms, res);
+
+	pbx_builtin_setvar_helper(chan, "FAXSTATUS", details->result);
+	pbx_builtin_setvar_helper(chan, "FAXERROR", details->error);
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", details->resultstr);
+	pbx_builtin_setvar_helper(chan, "REMOTESTATIONID", details->remotestationid);
+	pbx_builtin_setvar_helper(chan, "FAXBITRATE", details->transfer_rate);
+	pbx_builtin_setvar_helper(chan, "FAXRESOLUTION", details->resolution);
+
+	snprintf(tbuf, sizeof(tbuf), "%d", details->pages_transferred);
+	pbx_builtin_setvar_helper(chan, "FAXPAGES", tbuf);
+
+	ast_atomic_fetchadd_int(&faxregistry.fax_complete, 1);
+	if (!strcasecmp(details->result, "FAILED")) {
+		ast_atomic_fetchadd_int(&faxregistry.fax_failures, 1);
+	}
+
+	if (fax) {
+		ao2_lock(faxregistry.container);
+		ao2_unlink(faxregistry.container, fax);
+		ao2_unlock(faxregistry.container);
+		ao2_ref(fax, -1);
+	}
+
+	/* if the channel is still alive, and we changed its read/write formats,
+	 * restore them now
+	 */
+	if (chancount) {
+		if (orig_read_format) {
+			ast_set_read_format(chan, orig_read_format);
+		}
+		if (orig_write_format) {
+			ast_set_write_format(chan, orig_write_format);
+		}
+	}
+
+disable_t38:
+	if (disable_t38 &&
+	    (ast_channel_get_t38_state(chan) == T38_STATE_NEGOTIATED)) {
+		struct ast_control_t38_parameters t38_parameters = { .request_response = AST_T38_REQUEST_TERMINATE, };
+
+		if (ast_indicate_data(chan, AST_CONTROL_T38_PARAMETERS, &t38_parameters, sizeof(t38_parameters)) == 0) {
+			/* wait up to five seconds for negotiation to complete */
+			unsigned int timeout = 5000;
+			int ms;
+			
+			ast_debug(1, "Shutting down T.38 on %s\n", chan->name);
+			while (timeout > 0) {
+				ms = ast_waitfor(chan, 1000);
+				if (ms < 0) {
+					ast_log(LOG_WARNING, "something bad happened while channel '%s' was polling.\n", chan->name);
+					return -1;
+				}
+				if (!ms) {
+					/* nothing happened */
+					if (timeout > 0) {
+						timeout -= 1000;
+						continue;
+					} else {
+						ast_log(LOG_WARNING, "channel '%s' timed-out during the T.38 shutdown.\n", chan->name);
+						break;
+					}
+				}
+				if (!(frame = ast_read(chan))) {
+					return -1;
+				}
+				if ((frame->frametype == AST_FRAME_CONTROL) &&
+				    (frame->subclass.integer == AST_CONTROL_T38_PARAMETERS) &&
+				    (frame->datalen == sizeof(t38_parameters))) {
+					struct ast_control_t38_parameters *parameters = frame->data.ptr;
+					
+					switch (parameters->request_response) {
+					case AST_T38_TERMINATED:
+						ast_debug(1, "Shut down T.38 on %s\n", chan->name);
+						break;
+					case AST_T38_REFUSED:
+						ast_log(LOG_WARNING, "channel '%s' refused to disable T.38\n", chan->name);
+						break;
+					default:
+						ast_log(LOG_ERROR, "channel '%s' failed to disable T.38\n", chan->name);
+						break;
+					}
+					ast_frfree(frame);
+					break;
+				}
+				ast_frfree(frame);
+			}
+		}
+	}
+
+	/* return the chancount so the calling function can determine if the channel hungup during this FAX session or not */
+	return chancount;
+}
+
+/*! \brief initiate a receive FAX session */
+static int receivefax_exec(struct ast_channel *chan, const char *data)
+{
+	char *parse;
+	int channel_alive;
+	struct ast_fax_session_details *details;
+	struct ast_fax_document *doc;
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(filename);
+		AST_APP_ARG(options);
+	);
+	struct ast_flags opts = { 0, };
+	struct manager_event_info info;
+
+	if (ast_strlen_zero(data)) {
+		ast_log(LOG_WARNING, "%s requires an argument (filename[,options])\n", app_receivefax);
+		return -1;
+	}
+	parse = ast_strdupa(data);
+	AST_STANDARD_APP_ARGS(args, parse);
+	
+	/* initialize output channel variables */
+	pbx_builtin_setvar_helper(chan, "FAXSTATUS", "FAILED");
+	pbx_builtin_setvar_helper(chan, "FAXERROR", "Application Problems");
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", "Invalid application arguments.");
+	pbx_builtin_setvar_helper(chan, "REMOTESTATIONID", NULL);
+	pbx_builtin_setvar_helper(chan, "FAXPAGES", "0");
+	pbx_builtin_setvar_helper(chan, "FAXBITRATE", NULL);
+	pbx_builtin_setvar_helper(chan, "FAXRESOLUTION", NULL);
+
+	if (!ast_strlen_zero(args.options) &&
+	    ast_app_parse_options(fax_exec_options, &opts, NULL, args.options)) {
+		return -1;
+	}
+	if (ast_strlen_zero(args.filename)) {
+		ast_log(LOG_WARNING, "%s requires an argument (filename[,options])\n", app_receivefax);
+		return -1;
+	}
+
+	/* check for unsupported FAX application options */
+	if (ast_test_flag(&opts, OPT_CALLERMODE) || ast_test_flag(&opts, OPT_CALLEDMODE)) {
+		ast_log(LOG_WARNING, "%s does not support polling\n", app_receivefax);
+		return -1;
+	}
+	
+	/* make sure the channel is up */
+	if (chan->_state != AST_STATE_UP) {
+		if (ast_answer(chan)) {
+			ast_log(LOG_WARNING, "Channel '%s' failed answer attempt.\n", chan->name);
+			return -1;
+		}
+	}
+
+	ast_atomic_fetchadd_int(&faxregistry.fax_rx_attempts, 1);
+
+	pbx_builtin_setvar_helper(chan, "FAXERROR", "Channel Problems");
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", "Error before FAX transmission started.");
+
+	/* Get a FAX session details structure from the channel's FAX datastore and create one if
+ 	 * it does not already exist. */
+	if (!(details = find_or_create_details(chan))) {
+		ast_log(LOG_ERROR, "System cannot provide memory for session requirements.\n");
+		return -1;
+	}
+
+	if (!(doc = ast_calloc(1, sizeof(*doc) + strlen(args.filename) + 1))) {
+		ast_log(LOG_ERROR, "System cannot provide memory for session requirements.\n");
+		ao2_ref(details, -1);
+		return -1;
+	}
+
+	strcpy(doc->filename, args.filename);
+	AST_LIST_INSERT_TAIL(&details->documents, doc, next);
+
+	ast_verb(3, "Channel '%s' receiving FAX '%s'\n", chan->name, args.filename);
+
+	details->caps = AST_FAX_TECH_RECEIVE;
+
+	/* check for debug */
+	if (ast_test_flag(&opts, OPT_DEBUG) || global_fax_debug) {
+		details->option.debug = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	/* check for request for status events */
+	if (ast_test_flag(&opts, OPT_STATUS)) {
+		details->option.statusevents = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	if ((ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE) ||
+	    ast_test_flag(&opts, OPT_ALLOWAUDIO)) {
+		details->option.allow_audio = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	if ((channel_alive = generic_fax_exec(chan, details)) < 0) {
+		ast_atomic_fetchadd_int(&faxregistry.fax_failures, 1);
+	}
+	
+	/* send out the AMI completion event */
+	ast_channel_lock(chan);
+
+	get_manager_event_info(chan, &info);
+	manager_event(EVENT_FLAG_CALL,
+		      "ReceiveFAX", 
+		      "Channel: %s\r\n"
+		      "Context: %s\r\n"
+		      "Exten: %s\r\n"
+		      "CallerID: %s\r\n"
+		      "RemoteStationID: %s\r\n"
+		      "LocalStationID: %s\r\n"
+		      "PagesTransferred: %s\r\n"
+		      "Resolution: %s\r\n"
+		      "TransferRate: %s\r\n"
+		      "FileName: %s\r\n",
+		      chan->name,
+		      info.context,
+		      info.exten,
+		      info.cid,
+		      pbx_builtin_getvar_helper(chan, "REMOTESTATIONID"),
+		      pbx_builtin_getvar_helper(chan, "LOCALSTATIONID"),
+		      pbx_builtin_getvar_helper(chan, "FAXPAGES"),
+		      pbx_builtin_getvar_helper(chan, "FAXRESOLUTION"),
+		      pbx_builtin_getvar_helper(chan, "FAXBITRATE"),
+		      args.filename);
+	ast_channel_unlock(chan);
+
+	ao2_ref(details, -1);
+
+	/* If the channel hungup return -1; otherwise, return 0 to continue in the dialplan */
+	return (!channel_alive) ? -1 : 0;
+}
+
+/*! \brief initiate a send FAX session */
+static int sendfax_exec(struct ast_channel *chan, const char *data)
+{
+	char *parse;
+	int channel_alive;
+	struct ast_fax_session_details *details;
+	struct ast_fax_document *doc;
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(filename);
+		AST_APP_ARG(options);
+	);
+	struct ast_flags opts = { 0, };
+	struct manager_event_info info;
+
+	if (ast_strlen_zero(data)) {
+		ast_log(LOG_WARNING, "%s requires an argument (filename[,options])\n", app_sendfax);
+		return -1;
+	}
+	parse = ast_strdupa(data);
+	AST_STANDARD_APP_ARGS(args, parse);
+
+	/* initialize output channel variables */
+	pbx_builtin_setvar_helper(chan, "FAXSTATUS", "FAILED");
+	pbx_builtin_setvar_helper(chan, "FAXERROR", "Application Problems");
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", "Invalid application arguments.");
+	pbx_builtin_setvar_helper(chan, "REMOTESTATIONID", NULL);
+	pbx_builtin_setvar_helper(chan, "FAXPAGES", "0");
+	pbx_builtin_setvar_helper(chan, "FAXBITRATE", NULL);
+	pbx_builtin_setvar_helper(chan, "FAXRESOLUTION", NULL);
+
+	if (!ast_strlen_zero(args.options) &&
+	    ast_app_parse_options(fax_exec_options, &opts, NULL, args.options)) {
+		return -1;
+	}
+	if (ast_strlen_zero(args.filename)) {
+		ast_log(LOG_WARNING, "%s requires an argument (filename[,options])\n", app_sendfax);
+		return -1;
+	}
+	
+	/* check for unsupported FAX application options */
+	if (ast_test_flag(&opts, OPT_CALLERMODE) || ast_test_flag(&opts, OPT_CALLEDMODE)) {
+		ast_log(LOG_WARNING, "%s does not support polling\n", app_sendfax);
+		return -1;
+	}
+
+	if (access(args.filename, (F_OK | R_OK)) < 0) {
+		ast_log(LOG_ERROR, "access failure.  Verify '%s' exists and check permissions.\n", args.filename);
+		return -1;
+	}
+	
+	/* make sure the channel is up */
+	if (chan->_state != AST_STATE_UP) {
+		if (ast_answer(chan)) {
+			ast_log(LOG_WARNING, "Channel '%s' failed answer attempt.\n", chan->name);
+			return -1;
+		}
+	}
+
+	ast_atomic_fetchadd_int(&faxregistry.fax_tx_attempts, 1);
+	
+	pbx_builtin_setvar_helper(chan, "FAXERROR", "Channel Problems");
+	pbx_builtin_setvar_helper(chan, "FAXSTATUSSTRING", "Error before FAX transmission started.");
+
+	/* Get a requirement structure and set it.  This structure is used
+	 * to tell the FAX technology module about the higher level FAX session */
+	if (!(details = find_or_create_details(chan))) {
+		ast_log(LOG_ERROR, "System cannot provide memory for session requirements.\n");
+		return -1;
+	}
+
+	if (!(doc = ast_calloc(1, sizeof(*doc) + strlen(args.filename) + 1))) {
+		ast_log(LOG_ERROR, "System cannot provide memory for session requirements.\n");
+		ao2_ref(details, -1);
+		return -1;
+	}
+
+	strcpy(doc->filename, args.filename);
+	AST_LIST_INSERT_TAIL(&details->documents, doc, next);
+
+	ast_verb(3, "Channel '%s' sending FAX '%s'\n", chan->name, args.filename);
+	
+	details->caps = AST_FAX_TECH_SEND;
+
+	/* check for debug */
+	if (ast_test_flag(&opts, OPT_DEBUG) || global_fax_debug) {
+		details->option.debug = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	/* check for request for status events */
+	if (ast_test_flag(&opts, OPT_STATUS)) {
+		details->option.statusevents = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	if ((ast_channel_get_t38_state(chan) == T38_STATE_UNAVAILABLE) ||
+	    ast_test_flag(&opts, OPT_ALLOWAUDIO)) {
+		details->option.allow_audio = AST_FAX_OPTFLAG_TRUE;
+	}
+
+	if ((channel_alive = generic_fax_exec(chan, details)) < 0) {
+		ast_atomic_fetchadd_int(&faxregistry.fax_failures, 1);
+	}
+	
+	/* send out the AMI completion event */
+	ast_channel_lock(chan);
+	get_manager_event_info(chan, &info);
+	manager_event(EVENT_FLAG_CALL,
+		      "SendFAX", 
+		      "Channel: %s\r\n"
+		      "Context: %s\r\n"
+		      "Exten: %s\r\n"
+		      "CallerID: %s\r\n"
+		      "RemoteStationID: %s\r\n"
+		      "LocalStationID: %s\r\n"
+		      "PagesTransferred: %s\r\n"
+		      "Resolution: %s\r\n"
+		      "TransferRate: %s\r\n"
+		      "FileName: %s\r\n",
+		      chan->name,
+		      info.context,
+		      info.exten,
+		      info.cid,
+		      pbx_builtin_getvar_helper(chan, "REMOTESTATIONID"),
+		      pbx_builtin_getvar_helper(chan, "LOCALSTATIONID"),
+		      pbx_builtin_getvar_helper(chan, "FAXPAGES"),
+		      pbx_builtin_getvar_helper(chan, "FAXRESOLUTION"),
+		      pbx_builtin_getvar_helper(chan, "FAXBITRATE"),
+		      args.filename);
+	ast_channel_unlock(chan);
+
+	ao2_ref(details, -1);
+
+	/* If the channel hungup return -1; otherwise, return 0 to continue in the dialplan */
+	return (!channel_alive) ? -1 : 0;
+}
+
+/*! \brief hash callback for ao2 */
+static int session_hash_cb(const void *obj, const int flags)
+{
+	const struct ast_fax_session *s = obj;
+
+	return s->id;
+}
+
+/*! \brief compare callback for ao2 */
+static int session_cmp_cb(void *obj, void *arg, int flags)
+{
+	struct ast_fax_session *lhs = obj, *rhs = arg;
+
+	return (lhs->id == rhs->id) ? CMP_MATCH | CMP_STOP : 0;
+}
+
+/*! \brief FAX session tab completion */
+static char *fax_session_tab_complete(struct ast_cli_args *a) 
+{
+	int tklen;
+	int wordnum = 0;
+	char *name = NULL;
+	struct ao2_iterator i;
+	struct ast_fax_session *s;
+	char tbuf[5];
+
+	if (a->pos != 3) {
+		return NULL;
+	}
+
+	tklen = strlen(a->word);
+	i = ao2_iterator_init(faxregistry.container, 0);
+	while ((s = ao2_iterator_next(&i))) {
+		snprintf(tbuf, sizeof(tbuf), "%d", s->id);
+		if (!strncasecmp(a->word, tbuf, tklen) && ++wordnum > a->n) {
+			name = ast_strdup(tbuf);
+			ao2_ref(s, -1);
+			break;
+		}
+		ao2_ref(s, -1);
+	}
+	if (ao2_iterator_destroy != NULL) {
+		ao2_iterator_destroy(&i);
+	}
+	return name;
+}
+
+/*! \brief enable FAX debugging */
+static char *cli_fax_set_debug(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	int flag;
+	const char *what;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "fax set debug {on|off}";
+		e->usage = 
+			"Usage: fax set debug { on | off }\n"
+			"       Enable/Disable FAX debugging on new FAX sessions.  The basic FAX debugging will result in\n"
+			"       additional events sent to manager sessions with 'call' class permissions.  When\n"
+			"       verbosity is greater than '5' events will be displayed to the console and audio versus\n"
+			"       energy analysis will be performed and displayed to the console.\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	what = a->argv[e->args-1];      /* guaranteed to exist */
+	if (!strcasecmp(what, "on")) {
+		flag = 1;
+	} else if (!strcasecmp(what, "off")) {
+		flag = 0;
+	} else {
+		return CLI_SHOWUSAGE;
+	}
+
+	global_fax_debug = flag;
+	ast_cli(a->fd, "\n\nFAX Debug %s\n\n", (flag) ? "Enabled" : "Disabled");
+
+	return CLI_SUCCESS;
+}
+
+/*! \brief display registered FAX capabilities */
+static char *cli_fax_show_capabilities(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct fax_module *fax;
+	unsigned int num_modules = 0;
+	
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "fax show capabilities";
+		e->usage = 
+			"Usage: fax show capabilities\n"
+			"       Shows the capabilities of the registered FAX technology modules\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	ast_cli(a->fd, "\n\nRegistered FAX Technology Modules:\n\n");
+	AST_RWLIST_RDLOCK(&faxmodules);
+	AST_RWLIST_TRAVERSE(&faxmodules, fax, list) {
+		ast_cli(a->fd, "%-15s : %s\n%-15s : %s\n%-15s : ", "Type", fax->tech->type, "Description", fax->tech->description, "Capabilities");
+		fax->tech->cli_show_capabilities(a->fd);
+		num_modules++;
+	}
+	AST_RWLIST_UNLOCK(&faxmodules);
+	ast_cli(a->fd, "%d registered modules\n\n", num_modules);
+
+	return CLI_SUCCESS;
+}
+
+/*! \brief display details of a specified FAX session */
+static char *cli_fax_show_session(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct ast_fax_session *s, tmp;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "fax show session";
+		e->usage =
+			"Usage: fax show session <session number>\n"
+			"       Shows status of the named FAX session\n";
+		return NULL;
+	case CLI_GENERATE:
+		return fax_session_tab_complete(a);
+	}
+
+	if (a->argc != 4) {
+		return CLI_SHOWUSAGE;
+	}
+
+	if (sscanf(a->argv[3], "%d", &tmp.id) != 1) {
+		ast_log(LOG_ERROR, "invalid session id: '%s'\n", a->argv[3]);
+		return RESULT_SUCCESS;
+	}
+
+	ast_cli(a->fd, "\nFAX Session Details:\n--------------------\n\n");
+	s = ao2_find(faxregistry.container, &tmp, OBJ_POINTER);
+	if (s) {
+		s->tech->cli_show_session(s, a->fd);
+		ao2_ref(s, -1);
+	}
+	ast_cli(a->fd, "\n\n");
+
+	return CLI_SUCCESS;
+}
+	
+/*! \brief display fax stats */
+static char *cli_fax_show_stats(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct fax_module *fax;
+	
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "fax show stats";
+		e->usage =
+			"Usage: fax show stats\n"
+			"       Shows a statistical summary of FAX transmissions\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	ast_cli(a->fd, "\nFAX Statistics:\n---------------\n\n");
+	ast_cli(a->fd, "%-20.20s : %d\n", "Current Sessions", faxregistry.active_sessions);
+	ast_cli(a->fd, "%-20.20s : %d\n", "Transmit Attempts", faxregistry.fax_tx_attempts);
+	ast_cli(a->fd, "%-20.20s : %d\n", "Receive Attempts", faxregistry.fax_rx_attempts);
+	ast_cli(a->fd, "%-20.20s : %d\n", "Completed FAXes", faxregistry.fax_complete);
+	ast_cli(a->fd, "%-20.20s : %d\n", "Failed FAXes", faxregistry.fax_failures);
+	AST_RWLIST_RDLOCK(&faxmodules);
+	AST_RWLIST_TRAVERSE(&faxmodules, fax, list) {
+		fax->tech->cli_show_stats(a->fd);
+	}
+	AST_RWLIST_UNLOCK(&faxmodules);
+	ast_cli(a->fd, "\n\n");
+
+	return CLI_SUCCESS;
+}
+
+/*! \brief display fax sessions */
+static char *cli_fax_show_sessions(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	struct ast_fax_session *s;
+	struct ao2_iterator i;
+	int session_count;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "fax show sessions";
+		e->usage =
+			"Usage: fax show sessions\n"
+			"       Shows the current FAX sessions\n";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	ast_cli(a->fd, "\nCurrent FAX Sessions:\n\n");
+	ast_cli(a->fd, "%-20.20s %-10.10s %-10.10s %-10.10s %-15.15s %-30.30s\n",
+		"Channel", "ID", "Type", "Operation", "State", "File");
+	i = ao2_iterator_init(faxregistry.container, 0);
+	while ((s = ao2_iterator_next(&i))) {
+		ao2_lock(s);
+		ast_cli(a->fd, "%-20.20s %-10d %-10.10s %-10.10s %-15.15s %-30.30s\n",
+			s->channame, s->id, s->tech->type, (s->details->caps & AST_FAX_TECH_SEND) ? "send" : "receive",
+			ast_fax_state_to_str(s->state), AST_LIST_FIRST(&s->details->documents)->filename);
+		ao2_unlock(s);
+		ao2_ref(s, -1);
+	}
+	if (ao2_iterator_destroy != NULL) {
+		ao2_iterator_destroy(&i);
+	}
+	session_count = ao2_container_count(faxregistry.container);
+	ast_cli(a->fd, "\n%d FAX sessions\n\n", session_count);
+
+	return CLI_SUCCESS;
+}
+
+static struct ast_cli_entry fax_cli[] = {
+	AST_CLI_DEFINE(cli_fax_set_debug, "Enable/Disable FAX debugging on new FAX sessions"),
+	AST_CLI_DEFINE(cli_fax_show_capabilities, "Show the capabilities of the registered FAX technology modules"),
+	AST_CLI_DEFINE(cli_fax_show_session, "Show the status of the named FAX sessions"),
+	AST_CLI_DEFINE(cli_fax_show_sessions, "Show the current FAX sessions"),
+	AST_CLI_DEFINE(cli_fax_show_stats, "Summarize FAX session history"),
+};
+
+/*! \brief configure res_fax */
+static int set_config(const char *config_file)
+{
+	struct ast_config *cfg;
+	struct ast_variable *v;
+	struct ast_flags config_flags = { 0 };
+
+	/* set defaults */	
+	general_options.minrate = RES_FAX_MINRATE;
+	general_options.maxrate = RES_FAX_MAXRATE;	
+	general_options.statusevents = RES_FAX_STATUSEVENTS;
+	general_options.modems = RES_FAX_MODEM;
+
+	/* read configuration */
+	if (!(cfg = ast_config_load2(config_file, "res_fax", config_flags))) {
+		ast_log(LOG_NOTICE, "Configuration file '%s' not found, using default options.\n", config_file);
+		return 0;
+	}
+	if (cfg == CONFIG_STATUS_FILEUNCHANGED) {
+		ast_clear_flag(&config_flags, CONFIG_FLAG_FILEUNCHANGED);
+		cfg = ast_config_load2(config_file, "res_fax", config_flags);
+	}
+
+	/* create configuration */
+	for (v = ast_variable_browse(cfg, "general"); v; v = v->next) {
+		int rate;
+
+		if (!strcasecmp(v->name, "minrate")) {
+			ast_debug(3, "reading minrate '%s' from configuration file\n", v->value);
+			if ((rate = fax_rate_str_to_int(v->value)) == -1) {
+				ast_config_destroy(cfg);
+				return -1;
+			}
+			general_options.minrate = rate;
+		} else if (!strcasecmp(v->name, "maxrate")) {
+			ast_debug(3, "reading maxrate '%s' from configuration file\n", v->value);
+			if ((rate = fax_rate_str_to_int(v->value)) == -1) {
+				ast_config_destroy(cfg);
+				return -1;
+			}
+			general_options.maxrate = rate;
+		} else if (!strcasecmp(v->name, "statusevents")) {
+			ast_debug(3, "reading statusevents '%s' from configuration file\n", v->value);
+			general_options.statusevents = ast_true(v->value);
+		} else if ((!strcasecmp(v->name, "modem")) || (!strcasecmp(v->name, "modems"))) {
+			general_options.modems = 0;
+			update_modem_bits(&general_options.modems, v->value);
+		}
+	}
+
+	ast_config_destroy(cfg);
+
+	return 0;
+}
+
+/*! \brief FAXOPT read function returns the contents of a FAX option */
+static int acf_faxopt_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
+{
+	struct ast_fax_session_details *details = find_details(chan);
+	int res = 0;
+
+	if (!details) {
+		ast_log(LOG_ERROR, "channel '%s' can't read FAXOPT(%s) because it has never been written.\n", chan->name, data);
+		return -1;
+	}
+	if (!strcasecmp(data, "ecm")) {
+		ast_copy_string(buf, details->option.ecm ? "yes" : "no", len);
+	} else if (!strcasecmp(data, "error")) {
+		ast_copy_string(buf, details->error, len);
+	} else if (!strcasecmp(data, "filename")) {
+		ast_copy_string(buf, AST_LIST_FIRST(&details->documents)->filename, len);
+	} else if (!strcasecmp(data, "headerinfo")) {
+		ast_copy_string(buf, details->headerinfo, len);
+	} else if (!strcasecmp(data, "localstationid")) {
+		ast_copy_string(buf, details->localstationid, len);
+	} else if (!strcasecmp(data, "maxrate")) {
+		snprintf(buf, len, "%d", details->maxrate);
+	} else if (!strcasecmp(data, "minrate")) {
+		snprintf(buf, len, "%d", details->minrate);
+	} else if (!strcasecmp(data, "pages")) {
+		snprintf(buf, len, "%d", details->pages_transferred);
+	} else if (!strcasecmp(data, "rate")) {
+		ast_copy_string(buf, details->transfer_rate, len);
+	} else if (!strcasecmp(data, "remotestationid")) {
+		ast_copy_string(buf, details->remotestationid, len);
+	} else if (!strcasecmp(data, "resolution")) {
+		ast_copy_string(buf, details->resolution, len);
+	} else if (!strcasecmp(data, "sessionid")) {
+		snprintf(buf, len, "%d", details->id);
+	} else if (!strcasecmp(data, "status")) {
+		ast_copy_string(buf, details->result, len);
+	} else if (!strcasecmp(data, "statusstr")) {
+		ast_copy_string(buf, details->resultstr, len);
+	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
+		ast_fax_modem_to_str(details->modems, buf, len);
+	} else {
+		ast_log(LOG_WARNING, "channel '%s' can't read FAXOPT(%s) because it is unhandled!\n", chan->name, data);
+		res = -1;
+	}
+	ao2_ref(details, -1);
+
+	return res;
+}
+
+/*! \brief FAXOPT write function modifies the contents of a FAX option */
+static int acf_faxopt_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
+{
+	int res = 0;
+	struct ast_fax_session_details *details;
+
+	if (!(details = find_or_create_details(chan))) {
+		ast_log(LOG_WARNING, "channel '%s' can't set FAXOPT(%s) to '%s' because it failed to create a datastore.\n", chan->name, data, value);
+		return -1;
+	}
+	ast_debug(3, "channel '%s' setting FAXOPT(%s) to '%s'\n", chan->name, data, value);
+
+	if (!strcasecmp(data, "ecm")) {
+		details->option.ecm = ast_true(value) ? 1 : 0;
+	} else if (!strcasecmp(data, "headerinfo")) {
+		ast_string_field_set(details, headerinfo, value);
+	} else if (!strcasecmp(data, "localstationid")) {
+		ast_string_field_set(details, localstationid, value);
+	} else if (!strcasecmp(data, "maxrate")) {
+		details->maxrate = fax_rate_str_to_int(value);
+	} else if (!strcasecmp(data, "minrate")) {
+		details->minrate = fax_rate_str_to_int(value);
+	} else if ((!strcasecmp(data, "modem")) || (!strcasecmp(data, "modems"))) {
+		update_modem_bits(&details->modems, value);
+	} else {
+		ast_log(LOG_WARNING, "channel '%s' set FAXOPT(%s) to '%s' is unhandled!\n", chan->name, data, value);
+		res = -1;
+	}
+
+	ao2_ref(details, -1);
+
+	return res;
+}
+
+/*! \brief FAXOPT dialplan function */
+struct ast_custom_function acf_faxopt = {
+	.name = "FAXOPT",
+	.synopsis = "Set options for use with the SendFAX and ReceiveFAX functions, or read options after a FAX transmission completes",
+	.syntax = 
+"FAXOPT(<option>)\n"
+"  To write an option:\n"
+"     exten => blah,n,Set(FAXOPT(minrate)=4800)\n"
+"  To read an option:\n"
+"     exten => blah,n,NoOp(result: ${FAXOPT(status)})",
+	.desc =
+"The following table outlines the <options> that can be used with FAXOPT\n\n"
+"  OPTION             TYPE     DESCRIPTION\n"
+"  ------             ----     -----------\n"
+"  ecm                 RW      Specify Error Correction Mode (ECM) with 'yes', disable with 'no'.\n"
+"  error               RO      Read the FAX transmission error upon failure.\n"
+"  filename            RO      Read the filename of the FAX transmission.\n"
+"  headerinfo          RW      Specify or read the FAX header.\n"
+"  localstationid      RW      Specify or read the local station identification\n"
+"  maxrate             RW      Specify or read the maximum transfer rate before transmission\n"
+"  minrate             RW      Specify or read the minimum transfer rate before transmission\n"
+"  modem               RW      Specify or read the FAX modem\n"
+"  pages               RO      Read the number of pages transferred\n"
+"  rate                RO      Read the negotiated transmission rate\n"
+"  remotestationid     RO      Read the remote station identification after the transmission\n"
+"  resolution          RO      Read the negotiated image resolution after the transmission\n"
+"  sessionid           RO      Read the session ID of the FAX transmission\n"
+"  status              RO      Read the result status of the FAX transmission\n"
+"  statusstr           RO      Read a verbose result status of the FAX transmission\n"
+"\n  RO : Read Only\n  RW : Read/Write\n  WO : Write Only\n"
+"",
+	.read = acf_faxopt_read,
+	.write = acf_faxopt_write,
+};
+
+/*! \brief unload res_fax */
+static int unload_module(void)
+{
+	ast_cli_unregister_multiple(fax_cli, ARRAY_LEN(fax_cli));
+	
+	if (ast_custom_function_unregister(&acf_faxopt) < 0) {
+		ast_log(LOG_WARNING, "failed to unregister function '%s'\n", acf_faxopt.name);
+	}
+
+	if (ast_unregister_application(app_sendfax) < 0) {
+		ast_log(LOG_WARNING, "failed to unregister '%s'\n", app_sendfax);
+	}
+
+	if (ast_unregister_application(app_receivefax) < 0) {
+		ast_log(LOG_WARNING, "failed to unregister '%s'\n", app_receivefax);
+	}
+
+	ao2_ref(faxregistry.container, -1);
+
+	return 0;
+}
+
+/*! \brief load res_fax */
+static int load_module(void)
+{
+	int res;
+
+	/* initialize the registry */
+	faxregistry.active_sessions = 0;
+	if (!(faxregistry.container = ao2_container_alloc(FAX_MAXBUCKETS, session_hash_cb, session_cmp_cb))) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	
+	if (set_config(config) < 0) {
+		ast_log(LOG_ERROR, "failed to load configuration file '%s'\n", config);
+		ao2_ref(faxregistry.container, -1);
+		return AST_MODULE_LOAD_DECLINE;
+	}
+
+	/* register CLI operations and applications */
+	if (ast_register_application(app_sendfax, sendfax_exec, synopsis_sendfax, descrip_sendfax) < 0) {
+		ast_log(LOG_WARNING, "failed to register '%s'.\n", app_sendfax);
+		ao2_ref(faxregistry.container, -1);
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	if (ast_register_application(app_receivefax, receivefax_exec, synopsis_receivefax, descrip_receivefax) < 0) {
+		ast_log(LOG_WARNING, "failed to register '%s'.\n", app_receivefax);
+		ast_unregister_application(app_sendfax);
+		ao2_ref(faxregistry.container, -1);
+		return AST_MODULE_LOAD_DECLINE;
+	}
+	ast_cli_register_multiple(fax_cli, ARRAY_LEN(fax_cli));
+	res = ast_custom_function_register(&acf_faxopt);	
+
+	return res;
+}
+
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS, "Generic FAX Applications",
+		.load = load_module,
+		.unload = unload_module,
+	       );
diff --git a/res/res_fax.exports b/res/res_fax.exports
new file mode 100644
index 000000000..0ffe0b327
--- /dev/null
+++ b/res/res_fax.exports
@@ -0,0 +1,11 @@
+{
+	global:
+		ast_fax_tech_register;
+		ast_fax_tech_unregister;
+		ast_fax_session_unreference;
+		ast_fax_minrate;
+		ast_fax_maxrate;
+		ast_fax_state_to_str;
+	local:
+		*;
+};
diff --git a/res/res_fax_spandsp.c b/res/res_fax_spandsp.c
new file mode 100644
index 000000000..630cccb3b
--- /dev/null
+++ b/res/res_fax_spandsp.c
@@ -0,0 +1,762 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2009-2010, Digium, Inc.
+ *
+ * Matthew Nicholson <mnicholson@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! \file
+ *
+ * \brief Spandsp T.38 and G.711 FAX Resource
+ *
+ * \author Matthew Nicholson <mnicholson@digium.com>
+ *
+ * This module registers the Spandsp FAX technology with the res_fax module.
+ */
+
+/*** MODULEINFO
+		<depend>spandsp</depend>
+***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
+
+#define SPANDSP_EXPOSE_INTERNAL_STRUCTURES
+#include <spandsp.h>
+#include <spandsp/version.h>
+
+#include "asterisk/logger.h"
+#include "asterisk/module.h"
+#include "asterisk/strings.h"
+#include "asterisk/cli.h"
+#include "asterisk/utils.h"
+#include "asterisk/timing.h"
+#include "asterisk/astobj2.h"
+#include "asterisk/res_fax.h"
+
+#define SPANDSP_FAX_SAMPLES 160
+#define SPANDSP_FAX_TIMER_RATE 8000 / SPANDSP_FAX_SAMPLES	/* 50 ticks per second, 20ms, 160 samples per second */
+
+static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_token *token);
+static void spandsp_fax_destroy(struct ast_fax_session *s);
+static struct ast_frame *spandsp_fax_read(struct ast_fax_session *s);
+static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *f);
+static int spandsp_fax_start(struct ast_fax_session *s);
+static int spandsp_fax_cancel(struct ast_fax_session *s);
+static int spandsp_fax_switch_to_t38(struct ast_fax_session *s);
+
+static char *spandsp_fax_cli_show_capabilities(int fd);
+static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd);
+static char *spandsp_fax_cli_show_stats(int fd);
+
+static struct ast_fax_tech spandsp_fax_tech = {
+	.type = "Spandsp",
+	.description = "Spandsp FAX Driver",
+#if SPANDSP_RELEASE_DATE >= 20090220
+	/* spandsp 0.0.6 */
+	.version = SPANDSP_RELEASE_DATETIME_STRING,
+#else
+	/* spandsp 0.0.5
+	 * TODO: maybe we should determine the version better way
+	 */
+	.version = "pre-20090220",
+#endif
+	.caps = AST_FAX_TECH_AUDIO | AST_FAX_TECH_T38 | AST_FAX_TECH_SEND | AST_FAX_TECH_RECEIVE,
+	.new_session = spandsp_fax_new,
+	.destroy_session = spandsp_fax_destroy,
+	.read = spandsp_fax_read,
+	.write = spandsp_fax_write,
+	.start_session = spandsp_fax_start,
+	.cancel_session = spandsp_fax_cancel,
+	.switch_to_t38 = spandsp_fax_switch_to_t38,
+	.cli_show_capabilities = spandsp_fax_cli_show_capabilities,
+	.cli_show_session = spandsp_fax_cli_show_session,
+	.cli_show_stats = spandsp_fax_cli_show_stats,
+};
+
+struct spandsp_fax_stats {
+	int success;
+	int nofax;
+	int neg_failed;
+	int failed_to_train;
+	int rx_protocol_error;
+	int tx_protocol_error;
+	int protocol_error;
+	int retries_exceeded;
+	int file_error;
+	int mem_error;
+	int call_dropped;
+	int unknown_error;
+	int switched;
+};
+
+static struct {
+	ast_mutex_t lock;
+	struct spandsp_fax_stats g711;
+	struct spandsp_fax_stats t38;
+} spandsp_global_stats;
+
+struct spandsp_pvt {
+	unsigned int ist38:1;
+	unsigned int isdone:1;
+	fax_state_t fax_state;
+	t38_terminal_state_t t38_state;
+	t30_state_t *t30_state;
+	t38_core_state_t *t38_core_state;
+
+	struct spandsp_fax_stats *stats;
+
+	struct ast_timer *timer;
+	AST_LIST_HEAD(frame_queue, ast_frame) read_frames;
+};
+
+static void session_destroy(struct spandsp_pvt *p);
+static int t38_tx_packet_handler(t38_core_state_t *t38_core_state, void *data, const uint8_t *buf, int len, int count);
+static void t30_phase_e_handler(t30_state_t *t30_state, void *data, int completion_code);
+static void spandsp_log(int level, const char *msg);
+static int update_stats(struct spandsp_pvt *p, int completion_code);
+
+static void set_logging(logging_state_t *state, struct ast_fax_session_details *details);
+static void set_local_info(t30_state_t *t30_state, struct ast_fax_session_details *details);
+static void set_file(t30_state_t *t30_state, struct ast_fax_session_details *details);
+static void set_ecm(t30_state_t *t30_state, struct ast_fax_session_details *details);
+
+static void session_destroy(struct spandsp_pvt *p)
+{
+	struct ast_frame *f;
+
+	t30_terminate(p->t30_state);
+	p->isdone = 1;
+
+	ast_timer_close(p->timer);
+
+	fax_release(&p->fax_state);
+	t38_terminal_release(&p->t38_state);
+
+	while ((f = AST_LIST_REMOVE_HEAD(&p->read_frames, frame_list))) {
+		ast_frfree(f);
+	}
+}
+
+/*! \brief
+ *
+ */
+static int t38_tx_packet_handler(t38_core_state_t *t38_core_state, void *data, const uint8_t *buf, int len, int count)
+{
+	struct spandsp_pvt *p = data;
+	struct ast_frame fax_frame = {
+		.frametype = AST_FRAME_MODEM,
+		.subclass.integer = AST_MODEM_T38,
+		.src = "res_fax_spandsp_t38",
+	};
+
+	struct ast_frame *f = &fax_frame;
+
+
+	/* TODO: Asterisk does not provide means of resending the same packet multiple
+	  times so count is ignored at the moment */
+
+	AST_FRAME_SET_BUFFER(f, buf, 0, len);
+
+	if (!(f = ast_frisolate(f))) {
+		return -1;
+	}
+
+	/* no need to lock, this all runs in the same thread */
+	AST_LIST_INSERT_TAIL(&p->read_frames, f, frame_list);
+
+	return 0;
+}
+
+static int update_stats(struct spandsp_pvt *p, int completion_code)
+{
+	switch (completion_code) {
+	case T30_ERR_OK:
+		ast_atomic_fetchadd_int(&p->stats->success, 1);
+		break;
+
+	/* Link problems */
+	case T30_ERR_CEDTONE:            /*! The CED tone exceeded 5s */
+	case T30_ERR_T0_EXPIRED:         /*! Timed out waiting for initial communication */
+	case T30_ERR_T1_EXPIRED:         /*! Timed out waiting for the first message */
+	case T30_ERR_T3_EXPIRED:         /*! Timed out waiting for procedural interrupt */
+	case T30_ERR_HDLC_CARRIER:       /*! The HDLC carrier did not stop in a timely manner */
+	case T30_ERR_CANNOT_TRAIN:       /*! Failed to train with any of the compatible modems */
+		ast_atomic_fetchadd_int(&p->stats->failed_to_train, 1);
+		break;
+
+	case T30_ERR_OPER_INT_FAIL:      /*! Operator intervention failed */
+	case T30_ERR_INCOMPATIBLE:       /*! Far end is not compatible */
+	case T30_ERR_RX_INCAPABLE:       /*! Far end is not able to receive */
+	case T30_ERR_TX_INCAPABLE:       /*! Far end is not able to transmit */
+	case T30_ERR_NORESSUPPORT:       /*! Far end cannot receive at the resolution of the image */
+	case T30_ERR_NOSIZESUPPORT:      /*! Far end cannot receive at the size of image */
+		ast_atomic_fetchadd_int(&p->stats->neg_failed, 1);
+		break;
+
+	case T30_ERR_UNEXPECTED:         /*! Unexpected message received */
+		ast_atomic_fetchadd_int(&p->stats->protocol_error, 1);
+		break;
+
+	/* Phase E status values returned to a transmitter */
+	case T30_ERR_TX_BADDCS:          /*! Received bad response to DCS or training */
+	case T30_ERR_TX_BADPG:           /*! Received a DCN from remote after sending a page */
+	case T30_ERR_TX_ECMPHD:          /*! Invalid ECM response received from receiver */
+	case T30_ERR_TX_GOTDCN:          /*! Received a DCN while waiting for a DIS */
+	case T30_ERR_TX_INVALRSP:        /*! Invalid response after sending a page */
+	case T30_ERR_TX_NODIS:           /*! Received other than DIS while waiting for DIS */
+	case T30_ERR_TX_PHBDEAD:         /*! Received no response to DCS, training or TCF */
+	case T30_ERR_TX_PHDDEAD:         /*! No response after sending a page */
+	case T30_ERR_TX_T5EXP:           /*! Timed out waiting for receiver ready (ECM mode) */
+		ast_atomic_fetchadd_int(&p->stats->tx_protocol_error, 1);
+		break;
+
+	/* Phase E status values returned to a receiver */
+	case T30_ERR_RX_ECMPHD:          /*! Invalid ECM response received from transmitter */
+	case T30_ERR_RX_GOTDCS:          /*! DCS received while waiting for DTC */
+	case T30_ERR_RX_INVALCMD:        /*! Unexpected command after page received */
+	case T30_ERR_RX_NOCARRIER:       /*! Carrier lost during fax receive */
+	case T30_ERR_RX_NOEOL:           /*! Timed out while waiting for EOL (end Of line) */
+		ast_atomic_fetchadd_int(&p->stats->rx_protocol_error, 1);
+		break;
+	case T30_ERR_RX_NOFAX:           /*! Timed out while waiting for first line */
+		ast_atomic_fetchadd_int(&p->stats->nofax, 1);
+		break;
+	case T30_ERR_RX_T2EXPDCN:        /*! Timer T2 expired while waiting for DCN */
+	case T30_ERR_RX_T2EXPD:          /*! Timer T2 expired while waiting for phase D */
+	case T30_ERR_RX_T2EXPFAX:        /*! Timer T2 expired while waiting for fax page */
+	case T30_ERR_RX_T2EXPMPS:        /*! Timer T2 expired while waiting for next fax page */
+	case T30_ERR_RX_T2EXPRR:         /*! Timer T2 expired while waiting for RR command */
+	case T30_ERR_RX_T2EXP:           /*! Timer T2 expired while waiting for NSS, DCS or MCF */
+	case T30_ERR_RX_DCNWHY:          /*! Unexpected DCN while waiting for DCS or DIS */
+	case T30_ERR_RX_DCNDATA:         /*! Unexpected DCN while waiting for image data */
+	case T30_ERR_RX_DCNFAX:          /*! Unexpected DCN while waiting for EOM, EOP or MPS */
+	case T30_ERR_RX_DCNPHD:          /*! Unexpected DCN after EOM or MPS sequence */
+	case T30_ERR_RX_DCNRRD:          /*! Unexpected DCN after RR/RNR sequence */
+	case T30_ERR_RX_DCNNORTN:        /*! Unexpected DCN after requested retransmission */
+		ast_atomic_fetchadd_int(&p->stats->rx_protocol_error, 1);
+		break;
+
+	/* TIFF file problems */
+	case T30_ERR_FILEERROR:          /*! TIFF/F file cannot be opened */
+	case T30_ERR_NOPAGE:             /*! TIFF/F page not found */
+	case T30_ERR_BADTIFF:            /*! TIFF/F format is not compatible */
+	case T30_ERR_BADPAGE:            /*! TIFF/F page number tag missing */
+	case T30_ERR_BADTAG:             /*! Incorrect values for TIFF/F tags */
+	case T30_ERR_BADTIFFHDR:         /*! Bad TIFF/F header - incorrect values in fields */
+		ast_atomic_fetchadd_int(&p->stats->file_error, 1);
+		break;
+	case T30_ERR_NOMEM:              /*! Cannot allocate memory for more pages */
+		ast_atomic_fetchadd_int(&p->stats->mem_error, 1);
+		break;
+
+	/* General problems */
+	case T30_ERR_RETRYDCN:           /*! Disconnected after permitted retries */
+		ast_atomic_fetchadd_int(&p->stats->retries_exceeded, 1);
+		break;
+	case T30_ERR_CALLDROPPED:        /*! The call dropped prematurely */
+		ast_atomic_fetchadd_int(&p->stats->call_dropped, 1);
+		break;
+
+	/* Feature negotiation issues */
+	case T30_ERR_NOPOLL:             /*! Poll not accepted */
+	case T30_ERR_IDENT_UNACCEPTABLE: /*! Far end's ident is not acceptable */
+	case T30_ERR_SUB_UNACCEPTABLE:   /*! Far end's sub-address is not acceptable */
+	case T30_ERR_SEP_UNACCEPTABLE:   /*! Far end's selective polling address is not acceptable */
+	case T30_ERR_PSA_UNACCEPTABLE:   /*! Far end's polled sub-address is not acceptable */
+	case T30_ERR_SID_UNACCEPTABLE:   /*! Far end's sender identification is not acceptable */
+	case T30_ERR_PWD_UNACCEPTABLE:   /*! Far end's password is not acceptable */
+	case T30_ERR_TSA_UNACCEPTABLE:   /*! Far end's transmitting subscriber internet address is not acceptable */
+	case T30_ERR_IRA_UNACCEPTABLE:   /*! Far end's internet routing address is not acceptable */
+	case T30_ERR_CIA_UNACCEPTABLE:   /*! Far end's calling subscriber internet address is not acceptable */
+	case T30_ERR_ISP_UNACCEPTABLE:   /*! Far end's internet selective polling address is not acceptable */
+	case T30_ERR_CSA_UNACCEPTABLE:   /*! Far end's called subscriber internet address is not acceptable */
+		ast_atomic_fetchadd_int(&p->stats->neg_failed, 1);
+		break;
+	default:
+		ast_atomic_fetchadd_int(&p->stats->unknown_error, 1);
+		ast_log(LOG_WARNING, "unknown FAX session result '%d' (%s)\n", completion_code, t30_completion_code_to_str(completion_code));
+		return -1;
+	}
+	return 0;
+}
+
+/*! \brief Phase E handler callback.
+ * \param t30_state the span t30 state
+ * \param data this will be the ast_fax_session
+ * \param completion_code the result of the fax session
+ *
+ * This function pulls stats from the spandsp stack and stores them for res_fax
+ * to use later.
+ */
+static void t30_phase_e_handler(t30_state_t *t30_state, void *data, int completion_code)
+{
+	struct ast_fax_session *s = data;
+	struct spandsp_pvt *p = s->tech_pvt;
+	char headerinfo[T30_MAX_PAGE_HEADER_INFO + 1];
+	const char *c;
+	t30_stats_t stats;
+
+	ast_debug(5, "FAX session '%d' entering phase E\n", s->id);
+
+	p->isdone = 1;
+
+	update_stats(p, completion_code);
+
+	t30_get_transfer_statistics(t30_state, &stats);
+
+	if (completion_code == T30_ERR_OK) {
+		ast_string_field_set(s->details, result, "SUCCESS");
+	} else {
+		ast_string_field_set(s->details, result, "FAILED");
+		ast_string_field_set(s->details, error, t30_completion_code_to_str(completion_code));
+	}
+
+	ast_string_field_set(s->details, resultstr, t30_completion_code_to_str(completion_code));
+
+	ast_debug(5, "FAX session '%d' completed with result: %s (%s)\n", s->id, s->details->result, s->details->resultstr);
+
+	if ((c = t30_get_tx_ident(t30_state))) {
+		ast_string_field_set(s->details, localstationid, c);
+	}
+
+	if ((c = t30_get_rx_ident(t30_state))) {
+		ast_string_field_set(s->details, remotestationid, c);
+	}
+
+#if SPANDSP_RELEASE_DATE >= 20090220
+	s->details->pages_transferred = (s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_rx : stats.pages_tx;
+#else
+	s->details->pages_transferred = stats.pages_transferred;
+#endif
+
+	ast_string_field_build(s->details, transfer_rate, "%d", stats.bit_rate);
+
+	ast_string_field_build(s->details, resolution, "%dx%d", stats.x_resolution, stats.y_resolution);
+
+	t30_get_tx_page_header_info(t30_state, headerinfo);
+	ast_string_field_set(s->details, headerinfo, headerinfo);
+}
+
+/*! \brief Send spandsp log messages to asterisk.
+ * \param level the spandsp logging level
+ * \param msg the log message
+ *
+ * \note This function is a callback function called by spandsp.
+ */
+static void spandsp_log(int level, const char *msg)
+{
+	if (level == SPAN_LOG_ERROR) {
+		ast_log(LOG_ERROR, "%s", msg);
+	} else if (level == SPAN_LOG_WARNING) {
+		ast_log(LOG_WARNING, "%s", msg);
+	} else {
+		ast_log(LOG_DEBUG, "%s", msg);
+	}
+}
+
+static void set_logging(logging_state_t *state, struct ast_fax_session_details *details)
+{
+	int level = SPAN_LOG_WARNING;
+
+        if (details->option.debug) {
+		level = SPAN_LOG_DEBUG_3;
+	}
+
+	span_log_set_message_handler(state, spandsp_log);
+	span_log_set_level(state, SPAN_LOG_SHOW_SEVERITY | SPAN_LOG_SHOW_PROTOCOL | level);
+}
+
+static void set_local_info(t30_state_t *t30_state, struct ast_fax_session_details *details)
+{
+	if (!ast_strlen_zero(details->localstationid)) {
+		t30_set_tx_ident(t30_state, details->localstationid);
+	}
+
+	if (!ast_strlen_zero(details->headerinfo)) {
+		t30_set_tx_page_header_info(t30_state, details->headerinfo);
+	}
+}
+
+static void set_file(t30_state_t *t30_state, struct ast_fax_session_details *details)
+{
+	if (details->caps & AST_FAX_TECH_RECEIVE) {
+		t30_set_rx_file(t30_state, AST_LIST_FIRST(&details->documents)->filename, -1);
+	} else {
+		/* if not AST_FAX_TECH_RECEIVE, assume AST_FAX_TECH_SEND, this
+		 * should be safe because we ensure either RECEIVE or SEND is
+		 * indicated in spandsp_fax_new() */
+		t30_set_tx_file(t30_state, AST_LIST_FIRST(&details->documents)->filename, -1, -1);
+	}
+}
+
+static void set_ecm(t30_state_t *t30_state, struct ast_fax_session_details *details)
+{
+	t30_set_ecm_capability(t30_state, (details->option.ecm == AST_FAX_OPTFLAG_DEFAULT) ? 1 : details->option.ecm );
+	t30_set_supported_compressions(t30_state, T30_SUPPORT_T4_1D_COMPRESSION | T30_SUPPORT_T4_2D_COMPRESSION | T30_SUPPORT_T6_COMPRESSION);
+}
+
+/*! \brief create an instance of the spandsp tech_pvt for a fax session */
+static void *spandsp_fax_new(struct ast_fax_session *s, struct ast_fax_tech_token *token)
+{
+	struct spandsp_pvt *p;
+	int caller_mode;
+
+	if ((!(p = ast_calloc(1, sizeof(*p))))) {
+		ast_log(LOG_ERROR, "Cannot initialize the spandsp private FAX technology structure.\n");
+		goto e_return;
+	}
+
+	AST_LIST_HEAD_INIT(&p->read_frames);
+
+	if (s->details->caps & AST_FAX_TECH_RECEIVE) {
+		caller_mode = 0;
+	} else if (s->details->caps & AST_FAX_TECH_SEND) {
+		caller_mode = 1;
+	} else {
+		ast_log(LOG_ERROR, "Are we sending or receiving? The FAX requirements (capabilities: 0x%X) were not properly set.\n", s->details->caps);
+		goto e_free;
+	}
+
+	if (!(p->timer = ast_timer_open())) {
+		ast_log(LOG_ERROR, "Channel '%s' FAX session '%d' failed to create timing source.\n", s->channame, s->id);
+		goto e_free;
+	}
+
+	s->fd = ast_timer_fd(p->timer);
+
+	p->stats = &spandsp_global_stats.g711;
+
+	if (s->details->caps & AST_FAX_TECH_T38) {
+		if ((s->details->caps & AST_FAX_TECH_AUDIO) == 0) {
+			/* audio mode was not requested, start in T.38 mode */
+			p->ist38 = 1;
+			p->stats = &spandsp_global_stats.t38;
+		}
+
+		/* init t38 stuff */
+		t38_terminal_init(&p->t38_state, caller_mode, t38_tx_packet_handler, p);
+		set_logging(&p->t38_state.logging, s->details);
+	}
+
+	if (s->details->caps & AST_FAX_TECH_AUDIO) {
+		/* init audio stuff */
+		fax_init(&p->fax_state, caller_mode);
+		set_logging(&p->fax_state.logging, s->details);
+	}
+
+	s->state = AST_FAX_STATE_INITIALIZED;
+	return p;
+
+e_free:
+	ast_free(p);
+e_return:
+	return NULL;
+}
+
+/*! \brief Destroy a spandsp fax session.
+ */
+static void spandsp_fax_destroy(struct ast_fax_session *s)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+
+	session_destroy(p);
+	ast_free(p);
+	s->tech_pvt = NULL;
+	s->fd = -1;
+}
+
+/*! \brief Read a frame from the spandsp fax stack.
+ */
+static struct ast_frame *spandsp_fax_read(struct ast_fax_session *s)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+	uint8_t buffer[AST_FRIENDLY_OFFSET + SPANDSP_FAX_SAMPLES * sizeof(uint16_t)];
+	int16_t *buf = (int16_t *) (buffer + AST_FRIENDLY_OFFSET);
+	int samples;
+
+	struct ast_frame fax_frame = {
+		.frametype = AST_FRAME_VOICE,
+		.subclass.codec = AST_FORMAT_SLINEAR,
+		.src = "res_fax_spandsp_g711",
+	};
+
+	struct ast_frame *f = &fax_frame;
+
+	ast_timer_ack(p->timer, 1);
+
+	/* XXX do we need to lock here? */
+	if (p->isdone) {
+		s->state = AST_FAX_STATE_COMPLETE;
+		ast_debug(5, "FAX session '%d' is complete.\n", s->id);
+		return NULL;
+	}
+
+	if (p->ist38) {
+		t38_terminal_send_timeout(&p->t38_state, SPANDSP_FAX_SAMPLES);
+		if ((f = AST_LIST_REMOVE_HEAD(&p->read_frames, frame_list))) {
+			return f;
+		}
+	} else {
+		if ((samples = fax_tx(&p->fax_state, buf, SPANDSP_FAX_SAMPLES)) > 0) {
+			f->samples = samples;
+			AST_FRAME_SET_BUFFER(f, buffer, AST_FRIENDLY_OFFSET, samples * sizeof(int16_t));
+			return ast_frisolate(f);
+		}
+	}
+
+	return &ast_null_frame;
+}
+
+/*! \brief Write a frame to the spandsp fax stack.
+ * \param s a fax session
+ * \param f the frame to write
+ *
+ * \note res_fax does not currently use the return value of this function.
+ * Also the fax_rx() function never fails.
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ */
+static int spandsp_fax_write(struct ast_fax_session *s, const struct ast_frame *f)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+
+	/* XXX do we need to lock here? */
+	if (s->state == AST_FAX_STATE_COMPLETE) {
+		ast_log(LOG_WARNING, "FAX session '%d' is in the '%s' state.\n", s->id, ast_fax_state_to_str(s->state));
+		return -1;
+	}
+
+	if (p->ist38) {
+		return t38_core_rx_ifp_packet(p->t38_core_state, f->data.ptr, f->datalen, f->seqno);
+	} else {
+		return fax_rx(&p->fax_state, f->data.ptr, f->samples);
+	}
+}
+
+/*! \brief */
+static int spandsp_fax_start(struct ast_fax_session *s)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+
+	s->state = AST_FAX_STATE_OPEN;
+
+	if (p->ist38) {
+#if SPANDSP_RELEASE_DATE >= 20080725
+		/* for spandsp shaphots 0.0.6 and higher */
+		p->t30_state = &p->t38_state.t30;
+		p->t38_core_state = &p->t38_state.t38_fe.t38;
+#else
+		/* for spandsp releases 0.0.5 */
+		p->t30_state = &p->t38_state.t30_state;
+		p->t38_core_state = &p->t38_state.t38;
+#endif
+	} else {
+#if SPANDSP_RELEASE_DATE >= 20080725
+		/* for spandsp shaphots 0.0.6 and higher */
+		p->t30_state = &p->fax_state.t30;
+#else
+		/* for spandsp release 0.0.5 */
+		p->t30_state = &p->fax_state.t30_state;
+#endif
+	}
+
+	set_logging(&p->t30_state->logging, s->details);
+
+	/* set some parameters */
+	set_local_info(p->t30_state, s->details);
+	set_file(p->t30_state, s->details);
+	set_ecm(p->t30_state, s->details);
+
+	/* perhaps set_transmit_on_idle() should be called */
+
+	t30_set_phase_e_handler(p->t30_state, t30_phase_e_handler, s);
+
+	/* set T.38 parameters */
+	if (p->ist38) {
+		set_logging(&p->t38_core_state->logging, s->details);
+
+		t38_set_max_datagram_size(p->t38_core_state, s->details->their_t38_parameters.max_ifp);
+
+		if (s->details->their_t38_parameters.fill_bit_removal) {
+			t38_set_fill_bit_removal(p->t38_core_state, TRUE);
+		}
+
+		if (s->details->their_t38_parameters.transcoding_mmr) {
+			t38_set_mmr_transcoding(p->t38_core_state, TRUE);
+		}
+
+		if (s->details->their_t38_parameters.transcoding_jbig) {
+			t38_set_jbig_transcoding(p->t38_core_state, TRUE);
+		}
+	} else {
+		/* have the fax stack generate silence if it has no data to send */
+		fax_set_transmit_on_idle(&p->fax_state, 1);
+	}
+
+
+	/* start the timer */
+	if (ast_timer_set_rate(p->timer, SPANDSP_FAX_TIMER_RATE)) {
+		ast_log(LOG_ERROR, "FAX session '%d' error setting rate on timing source.\n", s->id);
+		return -1;
+	}
+
+	s->state = AST_FAX_STATE_ACTIVE;
+
+	return 0;
+}
+
+/*! \brief */
+static int spandsp_fax_cancel(struct ast_fax_session *s)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+	t30_terminate(p->t30_state);
+	p->isdone = 1;
+	return 0;
+}
+
+/*! \brief */
+static int spandsp_fax_switch_to_t38(struct ast_fax_session *s)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+
+	/* prevent the phase E handler from running, this is not a real termination */
+	t30_set_phase_e_handler(p->t30_state, NULL, NULL);
+
+	t30_terminate(p->t30_state);
+
+	s->details->option.switch_to_t38 = 1;
+	ast_atomic_fetchadd_int(&p->stats->switched, 1);
+
+	p->ist38 = 1;
+	p->stats = &spandsp_global_stats.t38;
+	spandsp_fax_start(s);
+
+	return 0;
+}
+
+/*! \brief */
+static char *spandsp_fax_cli_show_capabilities(int fd)
+{
+	ast_cli(fd, "SEND RECEIVE T.38 G.711\n\n");
+	return  CLI_SUCCESS;
+}
+
+/*! \brief */
+static char *spandsp_fax_cli_show_session(struct ast_fax_session *s, int fd)
+{
+	struct spandsp_pvt *p = s->tech_pvt;
+	t30_stats_t stats;
+
+	ao2_lock(s);
+	ast_cli(fd, "%-22s : %d\n", "session", s->id);
+	ast_cli(fd, "%-22s : %s\n", "operation", (s->details->caps & AST_FAX_TECH_RECEIVE) ? "Receive" : "Transmit");
+	ast_cli(fd, "%-22s : %s\n", "state", ast_fax_state_to_str(s->state));
+	if (s->state != AST_FAX_STATE_UNINITIALIZED) {
+		t30_get_transfer_statistics(p->t30_state, &stats);
+		ast_cli(fd, "%-22s : %s\n", "Last Status", t30_completion_code_to_str(stats.current_status));
+		ast_cli(fd, "%-22s : %s\n", "ECM Mode", stats.error_correcting_mode ? "Yes" : "No");
+		ast_cli(fd, "%-22s : %d\n", "Data Rate", stats.bit_rate);
+		ast_cli(fd, "%-22s : %dx%d\n", "Image Resolution", stats.x_resolution, stats.y_resolution);
+#if SPANDSP_RELEASE_DATE >= 20090220
+		ast_cli(fd, "%-22s : %d\n", "Page Number", (s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_rx : stats.pages_tx);
+#else
+		ast_cli(fd, "%-22s : %d\n", "Page Number", stats.pages_transferred);
+#endif
+		ast_cli(fd, "%-22s : %s\n", "File Name", s->details->caps & AST_FAX_TECH_RECEIVE ? p->t30_state->rx_file : p->t30_state->tx_file);
+
+		ast_cli(fd, "\nData Statistics:\n");
+#if SPANDSP_RELEASE_DATE >= 20090220
+		ast_cli(fd, "%-22s : %d\n", "Tx Pages", stats.pages_tx);
+		ast_cli(fd, "%-22s : %d\n", "Rx Pages", stats.pages_rx);
+#else
+		ast_cli(fd, "%-22s : %d\n", "Tx Pages", (s->details->caps & AST_FAX_TECH_SEND) ? stats.pages_transferred : 0);
+		ast_cli(fd, "%-22s : %d\n", "Rx Pages", (s->details->caps & AST_FAX_TECH_RECEIVE) ? stats.pages_transferred : 0);
+#endif
+		ast_cli(fd, "%-22s : %d\n", "Longest Bad Line Run", stats.longest_bad_row_run);
+		ast_cli(fd, "%-22s : %d\n", "Total Bad Lines", stats.bad_rows);
+	}
+	ao2_unlock(s);
+	ast_cli(fd, "\n\n");
+	return CLI_SUCCESS;
+}
+
+/*! \brief */
+static char *spandsp_fax_cli_show_stats(int fd)
+{
+	ast_mutex_lock(&spandsp_global_stats.lock);
+	ast_cli(fd, "\n%-20.20s\n", "Spandsp G.711");
+	ast_cli(fd, "%-20.20s : %d\n", "Success", spandsp_global_stats.g711.success);
+	ast_cli(fd, "%-20.20s : %d\n", "Switched to T.38", spandsp_global_stats.g711.switched);
+	ast_cli(fd, "%-20.20s : %d\n", "Call Dropped", spandsp_global_stats.g711.call_dropped);
+	ast_cli(fd, "%-20.20s : %d\n", "No FAX", spandsp_global_stats.g711.nofax);
+	ast_cli(fd, "%-20.20s : %d\n", "Negotation Failed", spandsp_global_stats.g711.neg_failed);
+	ast_cli(fd, "%-20.20s : %d\n", "Train Failure", spandsp_global_stats.g711.failed_to_train);
+	ast_cli(fd, "%-20.20s : %d\n", "Retries Exceeded", spandsp_global_stats.g711.retries_exceeded);
+	ast_cli(fd, "%-20.20s : %d\n", "Protocol Error", spandsp_global_stats.g711.protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "TX Protocol Error", spandsp_global_stats.g711.tx_protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "RX Protocol Error", spandsp_global_stats.g711.rx_protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "File Error", spandsp_global_stats.g711.file_error);
+	ast_cli(fd, "%-20.20s : %d\n", "Memory Error", spandsp_global_stats.g711.mem_error);
+	ast_cli(fd, "%-20.20s : %d\n", "Unknown Error", spandsp_global_stats.g711.unknown_error);
+
+	ast_cli(fd, "\n%-20.20s\n", "Spandsp T.38");
+	ast_cli(fd, "%-20.20s : %d\n", "Success", spandsp_global_stats.t38.success);
+	ast_cli(fd, "%-20.20s : %d\n", "Call Dropped", spandsp_global_stats.t38.call_dropped);
+	ast_cli(fd, "%-20.20s : %d\n", "No FAX", spandsp_global_stats.t38.nofax);
+	ast_cli(fd, "%-20.20s : %d\n", "Negotation Failed", spandsp_global_stats.t38.neg_failed);
+	ast_cli(fd, "%-20.20s : %d\n", "Train Failure", spandsp_global_stats.t38.failed_to_train);
+	ast_cli(fd, "%-20.20s : %d\n", "Retries Exceeded", spandsp_global_stats.t38.retries_exceeded);
+	ast_cli(fd, "%-20.20s : %d\n", "Protocol Error", spandsp_global_stats.t38.protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "TX Protocol Error", spandsp_global_stats.t38.tx_protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "RX Protocol Error", spandsp_global_stats.t38.rx_protocol_error);
+	ast_cli(fd, "%-20.20s : %d\n", "File Error", spandsp_global_stats.t38.file_error);
+	ast_cli(fd, "%-20.20s : %d\n", "Memory Error", spandsp_global_stats.t38.mem_error);
+	ast_cli(fd, "%-20.20s : %d\n", "Unknown Error", spandsp_global_stats.t38.unknown_error);
+	ast_mutex_unlock(&spandsp_global_stats.lock);
+
+	return CLI_SUCCESS;
+}
+
+/*! \brief unload res_fax_spandsp */
+static int unload_module(void)
+{
+	ast_fax_tech_unregister(&spandsp_fax_tech);
+	ast_mutex_destroy(&spandsp_global_stats.lock);
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+/*! \brief load res_fax_spandsp */
+static int load_module(void)
+{
+	ast_mutex_init(&spandsp_global_stats.lock);
+	spandsp_fax_tech.module = ast_module_info->self;
+	if (ast_fax_tech_register(&spandsp_fax_tech) < 0) {
+		ast_log(LOG_ERROR, "failed to register FAX technology\n");
+		return AST_MODULE_LOAD_DECLINE;
+	}
+
+	/* prevent logging to stderr */
+	span_set_message_handler(NULL);
+
+	return AST_MODULE_LOAD_SUCCESS;
+}
+
+
+AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_DEFAULT, "Spandsp G.711 and T.38 FAX Technologies",
+		.load = load_module,
+		.unload = unload_module,
+	       );