I posted a similar question on January 8. The following is the link to Robert's reply.
https://lists.cs.columbia.edu/pipermail/sip-implementors/2009-January/021332.html > -----Original Message----- > From: [email protected] [mailto:sip- > [email protected]] On Behalf Of Iñaki Baz > Castillo > Sent: Monday, February 09, 2009 5:00 AM > To: [email protected] > Subject: [Sip-implementors] "Reason-Header" in CANCEL through various > proxies > > Hi, RFC 3326 defines the "Reason" header to inform a UAS about why the > call was cancelled, this is: > > - alice calls bob. > - the proxy forks the INVITE to both locations in which bob is registered. > - bob_1 answers so the proxy generates a CANCEL to bob_2 and adds a > header to that CANCEL: > Reason: SIP ;cause=200 ;text="Call completed elsewhere" > - bob_2 phone receives the CANCEL and doesn't mark the incoming call > as missed since it has been replied elsewhere. > > But what about if there is other proxy in the middle? For example: > > - A pbx receives a incoming calls and does forking to al...@domaina > and b...@domainb. > - proxy_A receives the INVITE to al...@domaina and routes it to alice's > phone. > - proxy_B receives the INVITE to b...@domainb and routes it to bob's phone. > - alice answers so the PBX generates a CANCEL to proxy_B and adds > "Reason" header. > - Since CANCEL is hop by hop, proxy_B *will NOT* respect that "Reason" > header when it generates the CANCEL to bob's phone, so there is no way > bob's phone to be the call as answered elsewhere. > > This occurs due to CANCEL definition (hop by hop). However, > could/should a proxy respect extra-headers in an incoming CANCEL? > If not, how to handle the case I mean? (IMHO it's impossible). > > Thanks. > > > > -- > Iñaki Baz Castillo > <[email protected]> > > _______________________________________________ > Sip-implementors mailing list > [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
