youngerLYT wrote: > Hi, > How does SIP server discern whether a new incoming call is a video > call or a voice call? The differences between the video call messages > and the voice call messages are the content described in the SDP. > Usually, SIP server won't parse the content of the SDP in SIP messages.
By "SIP server" I assume you mean a proxy server. A user agent server is also a server, and it will of course look at the SDP to determine what kind of call it is. The simple answer is that a proxy doesn't generally care about whether the call is voice or video. Thus, there is no need to know. However, there are cases where call routing may depend on it. For example, a user has two devices. One does video only, the other audio only. The proxy will need to route video calls to the videophone, audio calls to the audiophone. This is done using the SIP caller preferences extension: http://www.ietf.org/internet-drafts/draft-ietf-sip-callerprefs-07.txt which would allow each client to register support for a particular media type. Then, the request itself can contain the Accept-Contact, Require-Contact or Reject-Contact header fields expressing preferences for routing the call based on the media type. -Jonathan R. -- Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Ave. Chief Scientist First Floor dynamicsoft East Hanover, NJ 07936 [EMAIL PROTECTED] FAX: (973) 952-5050 http://www.jdrosen.net PHONE: (973) 952-5000 http://www.dynamicsoft.com _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
