msc {
	hscale="3";
	ms [label="MS"], bsc [label="BSC"], mgw [label="MGW@MSC"], omsc [label="OsmoMSC"], osc [label="OsmoSIPcon"], sip [label="External SIP World"];
	|||;
	...		[label="Mobile Terminated call handled via osmo-sip-conector, OsmoMSC, OsmoMGW"];
	|||;

	sip box sip	[label="Somebody in SIP world dials a\nGSM subscriber"];
	osc <- sip	[label="SIP INVITE (from, to, SDP)"];
	osc box osc	[label="SDP -> bearer_capabilities"];
	omsc <- osc	[label="MNCC_SETUP_REQ (calling, called, bearer_cap)"];
	osc -> sip	[label="SIP 100 Trying"];
	bsc <- omsc	[label="BSSMAP PAGING"];
	ms <- bsc	[label="RR PAGING"];
	ms <-> bsc	[label="RR Establishment"];
	ms <-> omsc	[label="MM Procedures (Auth/Ciph/...)"];
	...;
	ms <- omsc	[label="CC SETUP (calling, bearer_cap)"];
	ms -> omsc	[label="CC CALL CONFIRMED (bearer_cap)"];
	omsc box omsc	[label="generate BSSMAP codec list from\nMS-negotiated bearer_cap"];
	bsc <- omsc	[label="BSSMAP ASSIGNMENT REQ"];
	ms <-> bsc	[label="RR ASSIGNMENT or RR MODE MODIFY"];
	bsc -> omsc	[label="BSSMAP ASSIGNMENT COMPL"];
	omsc box omsc	[label="determine chosen codec from\nBSSMAP Assignment"];
	mgw <- omsc	[label="MGCP CRCX (RAN-side, chosen codec)"];
	mgw -> omsc	[label="MGCP CRCX OK (RAN-side)"];
	omsc -> osc	[label="MNCC_CALL_CONF_IND"];

	omsc <- osc	[label="MNCC_RTP_CREATE.req"];
	mgw <- omsc	[label="MGCP CRCX (EXT-side)"];
	mgw box mgw	[label="If there is a common codec between RAN and CN, use that\nElse: Configure Transcoding in MGW"];
	mgw -> omsc	[label="MGCP CRCX OK (EXT-side)"];
	omsc -> osc	[label="MNCC_RTP_CREATE.resp (CN side IP/Port)"];
	...;
	ms box ms	[label="MS starts ringing"];
	ms -> omsc	[label="CC ALERTING"];
	omsc -> osc	[label="MNCC_ALERT_IND"];
	osc -> sip	[label="SIP 180 Ringing (SDP w/chosen codec?)"];
	...;
	...;
	ms box ms	[label="MT user accepts call"];
	ms -> omsc	[label="CC CONNECT"];
	omsc -> osc	[label="MNCC_SETUP_CNF"];
	osc -> sip	[label="SIP 200 OK (SDP w/chossen codec)"];
	osc <- sip	[label="SIP ACK"];
	omsc <- osc	[label="MNCC_RTP_CONNECT"];
	mgw <- omsc	[label="MGCP MDCX (MNCC-side, sendrecv)"];
	mgw -> omsc	[label="MGCP MDCX OK"];
	omsc <- osc	[label="MNCC_SETUP_COMPL_REQ"];
	ms <- omsc	[label="CC CONNECT ACK"];
	mgw <- omsc	[label="MGCP MDCX (RAN-side, sendrecv)"];
	mgw -> omsc	[label="MGCP MDCX OK"];
	...;
	ms box ms	[label="MT user releases call"];
	ms -> omsc	[label="CC DISCONNECT"];
	omsc -> osc	[label="MNCC_DISC_IND"];
	osc -> sip	[label="SIP BYE"];
	osc <- sip	[label="SIP 200 OK"];
	omsc <- osc	[label="MNCC_REL_REQ"];
	ms <- omsc	[label="CC RELEASE COMMAND"];
	ms -> omsc	[label="CC REELASE COMPLETE"];
	omsc -> osc	[label="MNCC_REL_CNF"];
	mgw <- omsc	[label="MGCP DLCX (all connections on EP)"];
	mgw -> omsc	[label="MGCP DLCX OK"];
	bsc <- omsc	[label="BSSMAP CLEAR CMD"];
	ms <-> bsc	[label="RR Disconnect"];
	bsc -> omsc	[label="BSSMAP CLEAR CMPL"];

}