Qsig Encapsulation Over SIP Encapsulation Over SIP Qsig audet@ @nortelnetworks nortelnetworks.com .com audet long@ long@nortelnetworks nortelnetworks.com .com mzonoun@nortelnetworks nortelnetworks.com .com mzonoun@
What is Qsig? • Qsig is a family of standards providing connectivity between corporate network switches, Centrex switches as well as corporate network to Centrex switches. • Qsig specifies a set of supplementary services, the service specific "Qsig" signalling protocols for the exchange of information between switches across an interface at the "Q" reference point. • Qsig basic call is a symmetrical (peer-to-peer) version of ISDN DSS1. • QSIG generic procedures provide support for the supplementary services. These procedures allow for standardized and proprietary supplementary services to coexist.
What is needed? • Transport of QSIG signaling between call servers as part of the payload of SIP messages. • Support of in-band tones and announcement • Transport of mid-call information in both directions — Qsig messages that do not map easily to SIP messages — Qsig supplementary service information — Notifications • All these requirements are similar to ISUP
Architecture SIP Qsig encapsulated SIP PBX CS CS PBX IP PSTN PSTN
What extensions are required for PBX signaling? • A “best current practices” for private network PBX signaling with QSIG as an alternative to ISUP — Mapping between QSIG and SIP • A SIP/QSIG MIME type • SIP INFO method • SIP 183 Session progress message
Illustrative example INVITE sip:14084955072@sc1.nortelnetworks.com SIP/2.0 From: sip:14085655675@sc10.nortelnetworks.com To: sip:14084955072@sc1.nortelnetworks.com Call-ID: 1231999021712095500999@sc12.nortelnetworks.com Content-Length: .. Content-Type: multipart/mixed; boundary=unique-boundary-1 MIME-Version: 1.0 --unique-boundary-1 Content-Type: application/SDP; charset=ISO-10646 v=0 o=audet 2890844526 2890842807 5 IN IP4 134.177.64.4 s=SDP seminar c=IN IP4 MG141.nortelnetworks.com t= 2873397496 2873404696 m=audio 9092 RTP/AVP 0 3 4 --unique-boundary-1 Content-type:application/QSIG;version=ISO Content-Transfer-Encoding: binary 08 02 55 55 05 04 02 90 90 18 03 a1 83 01 70 0a 89 31 34 30 38 34 39 35 35 30 37 32
Supporting Slides
Call setup with locally generated tones PSTN 1 Call server 1 Call server 2 PSTN 2 SETUP CALL PROC INVITE (SETUP) 100 TRYING SETUP CALL PROC ALERTING 180 RINGING (ALERTING) CONNECT ALERTING Locally 200 OK (CONNECT) generated CONNECT ringback ACK Two-way voice path
Call setup with far-end generated tones PSTN 1 Call server 1 Call server 2 PSTN 2 SETUP CALL PROC INVITE (SETUP) 100 TRYING SETUP Progress indicator = CALL PROC in-band 183 SESSION PROG tones In-band (CALL PROC) PROGRESS ringing Progress indicator = On-way voice path in-band CONNECT tones 200 OK (CONNECT) CONNECT ACK Two-way voice path
Call tear-down PSTN 1 Call server 1 Call server 2 PSTN 2 DISCONNECT RELEASE BYE (DISCONNECT) 200 OK RELEASE COMP DISCONNECT RELEASE RELEASE COMP
User busy with locally generated tones PSTN 1 Call server 1 Call server 2 PSTN 2 SETUP CALL PROC INVITE (SETUP) 100 TRYING SETUP Cause = RELEASE COMP user busy 600 BUSY everywhere (RELEASE COMP) DISCONNECT Locally generated RELEASE ringback (cause = busy) RELEASE COMP
User busy with far-end generated tones PSTN 1 Call server 1 Call server 2 PSTN 2 SETUP CALL PROC INVITE (SETUP) 100 TRYING SETUP Progress CALL PROC indicator = in-band 183 SESSION PROG Progress tones (CALL PROC) indicator = PROGRESS in-band On-way voice path In-band busy tones tone User hangs DISCONNECT up RELEASE BYE (DISCONNECT) 200 OK DISCONNECT RELEASE COMP RELEASE RELEASE COMP
Transfer of mid-call messages PSTN 1 Call server 1 Call server 2 PSTN 2 NOTIFY INFO (NOTIFY) 200 OK NOTIFY INFORMATION INFO (INFORMATION) 200 OK INFORMATION FACILITY INFO (FACILITY) 200 OK FACILITY
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