2009/9/28 Teodor Georgiev <teo...@visp.net.lb>: > > > Hi list, > > I am trying to implement something a little bit odd and against the RFC, but > hope will get some help anyways :) > > There is a SIP UAC (used for events notification) written by a person who has > left the project and will not fix it. > That SIP UAC has a really silly bug - it doesn't send back ACKs to 4XX//5XX > responses. I do not have access > to the source of his code so I can't fix the trouble there. > > Instead I am writing my own mini SIP stack that would send back the ACK on > behalf of the buggy UAC. > I have put my app on the way as a transparent SIP stateless proxy. The issue > here also is that I do not > keep a copy of the original INVITE, so I am trying to construct my ACK based > on the received 4XX message: >
> * I keep the From, To, Call-ID, From and VIA fields as-it-is from the 4XX > message Ok > * The Cseq is modified according to the RFC ACK for a [3456]XX response is part of the INVITE transaction so CSeq is not incremented. ACK for 2XX response is a new transaction, however CSeq is not incremented. This is, CSeq value in ACK for any response MUST match CSeq value in the INVITE. > * The Request URI - I am constructing it by myself, I know that the called > number is always 444302 Wrong. The RURI in an ACK for a [3456]XX response MUST match the RURI of the INVITE. The RURI only changes after establishing a dialog so UAC knows the exact location of UAS (by inspecting the "Contact" in the 2XX response. If an INVITE is rejected ([3456]XX response) then a dialog hasn't take place so the RURI in the ACK doesn't change. > However the other devices (Cisco 7960 SIP phones and SJPhone softphones) keep > resending me > the "Request Timeout" messages (or "NOT FOUND", if I configure them in a way > to not accept 444302 calls) Yes, it makes sense as you did two errors. -- Iñaki Baz Castillo <i...@aliax.net> _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
