The ISDN CPE side should not exclusively pick B channels normally.

Before this patch, Asterisk unconditionally picked B channels exclusively
on the CPE side and normally allowed alternative B channels on the network
side.  Now Asterisk does the opposite.

Reasons for the CPE side to normally not pick B channels exclusively:
*  For CPE point-to-multipoint mode (i.e. phone side), the CPE side does
not have enough information to exclusively pick B channels.  (There may be
other devices on the line.)
*  Q.931 gives preference to the network side picking B channels.
*  Some telcos require the CPE side to not pick B channels exclusively.

(closes issue #14383)
Reported by: mbrancaleoni


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@203908 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 5 insertions, 8 deletions

diff --git a/channels/chan_dahdi.c b/channels/chan_dahdi.c
index 46bc9ccec..d10ddb905 100644
--- a/channels/chan_dahdi.c
+++ b/channels/chan_dahdi.c
@@ -2463,15 +2463,12 @@ static int dahdi_call(struct ast_channel *ast, char *rdest, int timeout)
 			pri_set_crv(p->pri->pri, p->call, p->channel, 0);
 		}
 		p->digital = IS_DIGITAL(ast->transfercapability);
-		/* Add support for exclusive override */
-		if (p->priexclusive)
+
+		/* Should the picked channel be used exclusively? */
+		if (p->priexclusive || p->pri->nodetype == PRI_NETWORK) {
 			exclusive = 1;
-		else {
-		/* otherwise, traditional behavior */
-			if (p->pri->nodetype == PRI_NETWORK)
-				exclusive = 0;
-			else
-				exclusive = 1;
+		} else {
+			exclusive = 0;
 		}
 		
 		pri_sr_set_channel(sr, p->bearer ? PVT_TO_CHANNEL(p->bearer) : PVT_TO_CHANNEL(p), exclusive, 1);