That depends. The purpose of the trunk-context is analogous to a domain in an email address. It provides a "domain" in which trunk group names are unique. For example; if you'd like to use the same trkgrpa for an interconnect, but the carrier you're interconnecting with already has that trunk group name associated with another interconnect, by adding a trunk-context, you can make that overlapping name unique within the interconnecting carriers network. That said, trunk-contexts are actually required for a proper implementation of RFC 4904, so you should never have overlapping names, unless of course, you're both using the same context name as well :)
To put this all together; if you both agree on a trunk-group name of trkgrpa, your context is yahoo.com, and the interconnecting carrier's context is google.com, then under normal implementations your Contact header would read as `Contact: <sip:vivsingla;tgrp=trkgrpa;[email protected]>` and your Request-URI would read as `INVITE sip:otherparty;tgrp=trkgrpa;[email protected] SIP/2.0`. Joel Gerber Network Administrator Network Operations Eastlink E: [email protected]<mailto:[email protected]> T: 519.786.1241 From: Vivek Singla [mailto:[email protected]] Sent: March-20-13 1:07 PM To: Joel Gerber; [email protected] Subject: Re: [Sip-implementors] tgrp and trunk-context from RFC 4904 Thanks Joel. I have a scenario where system A sends SIP Invite to system B. The RURI has the trunk context value of system id A. The CONTACT header has the trunk context value of system A. Shouldnt RURI has the trunk context value of system id B? Vivek. From: Joel Gerber <[email protected]<mailto:[email protected]>> To: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Sent: Wednesday, March 20, 2013 6:28 AM Subject: Re: [Sip-implementors] tgrp and trunk-context from RFC 4904 The information located in the R-URI designates a destination trunk group, while the information in the contact header designates an origination trunk group. They can be the same, but they can also be different, depending on what your peering arrangements are like with the carrier/equipment you're interconnecting with. I have encountered some equipment that ignores the trunk group information specified in the R-URI and only honour what is located in the Contact header, so MMV. Joel Gerber Network Specialist Network Operations Eastlink E: [email protected]<mailto:[email protected]> T: 519.786.1241 -----Original Message----- From: [email protected]<mailto:[email protected]> [mailto:[email protected]<mailto:[email protected]>] On Behalf Of Vivek Singla Sent: March-19-13 7:22 PM To: [email protected]<mailto:[email protected]> Subject: [Sip-implementors] tgrp and trunk-context from RFC 4904 Hi, I am trying to find some information regarding populating RURI and CONTACT headers with the tgrp and trunk-context values. I am going through rfc 4904. My question is: In the outgoing SIP Invite from UAC, the values of tgrp and trunk-context, should they be same in RURI and CONTACT headers? I am thinking in the R-URI these values will be what is in the remote UAS and in CONTACT header, these values will be what is in the local UAC. Am I correct in assuming this? Vivek. _______________________________________________ Sip-implementors mailing list [email protected]<mailto:[email protected]> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected]<mailto:[email protected]> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
