Hi Neel, RFC3264 7 Offerer Processing of the Answer The offerer MAY immediately cease listening for media formats that were listed in the initial offer, but not present in the answer.
Therefore, UA A may not be able to receive G726. If UAs use G726, reINVITE will be needed. Shini >See below. > >> -----Original Message----- >> From: [email protected] [mailto:sip- >> [email protected]] On Behalf Of Michael >> Hirschbichler >> Sent: Friday, March 12, 2010 8:52 AM >> Cc: [email protected] >> Subject: Re: [Sip-implementors] Offer-answer question >> >> Thx, >> >> this is also my opinion. >> To point it down: there is no way to use G726 in *any* direction >> without >> Re-INVITEs - is this correct? >> >[Neel] >Since the offer contains G726, the endpoint A should be prepared to receive >G726. No Re >-INVITE is necessary. > >Thanks, >Neel. > >> BR >> Michael >> >> Am 12.03.2010 15:48, schrieb Arunachala: >> > Not entirely true. A& B can talk using both G729 and PCMA. Either >> one >> > can switch between these two codecs without the use of a reINVITE. >> > >> > -Arun >> > >> > On Fri, Mar 12, 2010 at 7:34 PM, Aneesh Naik<[email protected]> >> wrote: >> >> Hi Michael, >> >> >> >> This will not be allowed. A (UAC) has sent all the codecs it >> supports, >> >> and B (UAS) has respoded with the codecs it is willing to talk to A >> for this >> >> call. Only one codec will be negotiated for media transfer between A >> and B. >> >> In your example below, the negotiated codec is G.729, so both the >> parties >> >> must send media on G.729 codec. >> >> >> >> If the codec needs to change it between, then there can be a Re- >> NVITE to >> >> change the codec, and both parties once aggreed will start talking >> on that >> >> new codec negotiated. >> >> >> >> Thanks, >> >> Aneesh >> >> On Fri, Mar 12, 2010 at 7:14 PM, Michael Hirschbichler< >> >> [email protected]> wrote: >> >> >> >>> Hi all, >> >>> >> >>> In my specific test-case, client A sends an INVITE offering some >> codecs >> >>> and client B answers with a 200OK containing a subset of these >> codecs. >> >>> Is it allowed for client B to transmit media using a codec >> presented in >> >>> the offer of client A but not acknowledged in the answer of client >> B? >> >>> >> >>> e.g.: >> >>> >> >>> client A sends: >> >>> INVITE >> >>> m= G726, G729, G723, PCMA, PCMU >> >>> >> >>> client B responses: >> >>> 200OK >> >>> m= G729, PCMA >> >>> >> >>> the resulting media-exchange: >> >>> >> >>> A====G729====>B >> >>> A<====G726====B >> >>> >> >>> is this allowed? Must A accept the G726-media? >> >>> >> >>> BR and thx in advance >> >>> Michael _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
