Hi Nitin, As per your call flow the second INVITE contains SDP and UAS is not aware of if UAC has not send SDP in offer. It sees the offer coming in INVITE. This scenario must be handled by B2BUA which can send PRACK to Invite transaction it has created with UAS. For the initial call flow with UAC...u can choose to send 18X SDP with 100 Rel...which can get answer SDP in PRACK.
Regards Sunil Verma ESN: 877-5050 Ph: +919731245000 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Nitin Kapoor Sent: Thursday, June 10, 2010 11:24 PM To: [email protected] Subject: [Sip-implementors] Invite without SDP & getting 100rel in 18x Dear All, I have a call flow like this. UAC(SIP) -----> Invite/without SDP ------> B2BUA -----Invite/with SDP default port-----> UAS(SIP) Now as far as I know what RFC says that: "The initial offer MUST be in either an INVITE or, if not there, in the first reliable non-failure message from the UAS back to the UAC. In this specification, that is the final 2xx response" Here is what happening at my case that my source UA is sending me invite without SDP to my SBC and my SBC is forwarding the same to termination UA with default port as per the design. But from Termination side I am getting first 183 w/o SDP and others 2 with SDP before getting 200 OK w/ SDP in the correspondence of initial offer INVITE. And in those 183 I am getting "100rel" in REQUIRE header field which is not correct according to me. Because my understanding says that in those scenario where you are getting initial OFFER w/o SDP, PRACK should be not be negotiate before getting the 200 OK w/ SDP for the initial invite. Hence I am facing the media issue. Now I might be wrong too...Could any please help me on this and if need the traces then I can also share. Thanks, Nitin Kapoor _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors Please do not print this email unless it is absolutely necessary. The information contained in this electronic message and any attachments to this message are intended for the exclusive use of the addressee(s) and may contain proprietary, confidential or privileged information. If you are not the intended recipient, you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately and destroy all copies of this message and any attachments. WARNING: Computer viruses can be transmitted via email. The recipient should check this email and any attachments for the presence of viruses. The company accepts no liability for any damage caused by any virus transmitted by this email. www.wipro.com _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
