Doesn't RFC3960 talk about this very thing? -Arun
On Wed, May 12, 2010 at 1:14 PM, Paul Kyzivat <pkyzi...@cisco.com> wrote: > Technically, SDP in any 18x only serves to indicate where media should > be *sent*, and has nothing to do with whether you should receive media, > play received media, etc. > > Nor does receiving a 180 mean you should play local ringback. It merely > says "the other end is being alerted". Nor does receiving a 183 after > receiving a 183 after a 180 mean you should *not* play local ringback. > > If you have received a 180, you may want to play something indicating > the called device is alerting. If you are receiving media that you are > willing to render, you might want to do so in lieu of locally generated > ringback. > > Unless you use ICE or SRTP, SIP doesn't really specify any way to > determine if media you are receiving is media the callee intended for > you to receive, rather than spam. As a result, some implementations > refuse to render received media unless it comes from the address they > are to send media to (symmetric RTP). You can do that if you feel you > must, but recognize that you may miss valid media from some implementations. > > There is no perfect answer here. You can do pretty much as you wish. > (E.g. you aren't *required* to render any of the media you receive, even > after the call is established.) But you can also have a crappy > implementation that doesn't interoperate well with others if you make > unreasonable assumptions. > > Thanks, > Paul > > Kanumuri, Sreeram wrote: >> Nitin, >> >>> I checked the TO tag for both 18x and noticed that both are the same. >>> Do you think, that after sending 180 ringing(where local ringing should >>> generate), if my UAS is sending 183 without SDP will stop the local ringing? >> >> This is up to the implementation whether to play ringing (or) not. >> >> In this case, I feel you should stop the ringing after receiving 183 and >> show a different treatment to the originating UA (something like >> click,,click..) to indicate that the call is in progress... >> >> >> HTH, >> Sreeram. >> _______________________________________________ >> Sip-implementors mailing list >> Sip-implementors@lists.cs.columbia.edu >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors >> > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
