180 Ringing with SDP implies early media. This is required for
1) Interoperability with PSTN (Addresses the need for PSTN inband style altering) 2) To avoid media clipping. (If initial invite did not contain an offer) 3) Useful when terminating gateway wishes to play the Ring Back tone (for e.g. Ring back tone services). Hope this helps. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Paulo de Arruda Borelli Sent: Wednesday, January 25, 2006 2:29 PM To: [EMAIL PROTECTED] Cc: [EMAIL PROTECTED]; [email protected] Subject: Re: [Sip-implementors] 180 Ringing with SDP Hi Amar, I can't understand why are you talking about reliable responses... They are not necessarily related to the SDP usage. I can't find anything, on the RFC excerpts you selected, telling that SDP is ok in 180 responses. Would you clarify this why you selected these excerpts? Thank you Paulo. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 25, 2006 2:46 AM To: Paulo de Arruda Borelli Cc: [email protected]; [EMAIL PROTECTED] Subject: Re: [Sip-implementors] 180 Ringing with SDP Hi, As per the RFC 3262 any response between 101 to 199 can be sent reliably. From sec 3. "A UAS MUST NOT attempt to send a 100 (Trying) response reliably. Only provisional responses numbered 101 to 199 may be sent reliably. If the request did not include either a Supported or Require header field indicating this feature, the UAS MUST NOT send the provisional response reliably." From sec 4. "If a provisional response is received for an initial request, and that response contains a Require header field containing the option tag 100rel, the response is to be sent reliably. If the response is a 100 (Trying) (as opposed to 101 to 199), this option tag MUST be ignored, and the procedures below MUST NOT be used." So there is no harm in sending SDP in 180 ringing for early media. You should not restrict it only to 183. Rgds, Amar The greatest enemy of best is "good." If you're willing to accept "good" you'll never be the "Best." "Paulo de Arruda Borelli" <[EMAIL PROTECTED] To om.br> <[email protected]> Sent by: cc sip-implementors- [EMAIL PROTECTED] Subject ia.edu [Sip-implementors] 180 Ringing with SDP 01/25/2006 06:18 AM Hi, Why would an UAC send 180 Ringing with SDP? If it's supposed to use early media, then 183 Session Progress is more appropriate, right? In my understanding, 180 with SDP is contradictory. 180 means: "play a local ringback tone". But the SDP content means: open the media path (in my scenario, the original INVITE message did include SDP too). So what is the reason for using 180 with SDP in the scenario bellow? INVITE/SDP from A to B 180/SDP from B to A 200/SDP from B to A Thank you, Paulo A. Borelli Gerente de Engenharia / Engineering Manager TMais S.A. VoIPMais: +55-11-2626-1080, r. 1136 Cell: +55-11-9282-5990 <BLOCKED::mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED] <BLOCKED::http://www.tmais.com.br> www.tmais.com.br _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors *********************** FSS-Unclassified *********************** _______________________________________________ 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
