> From: Jaya krishna > The following lines from RFC 3856 seems contradictory. can you help me > to understand this clearly > > statement 1 (Section 5 Usage of Presence URIs ) : > > "If the subscriber is aware of both the protocol-independent pres URI > and the SIP or SIPS URI for the same presentity, and both are valid (as > discussed above) it SHOULD use the pres URI format. " > > Statement 2 (Section 5 Usage of Presence URIs ) : > > " When the pres URI is used, any proxies along the path of the SUBSCRIBE > request which do not understand the URI scheme will reject the request. > As such, it is expected that many systems will be initially deployed > that only provide users with a SIP URI." > > > Here the statement 1 mandates us with using pres and next statement says > it will be rejected. How to handle this situation. > > can a contact of SUBSCRIBE request be of PRES: scheme ?
To extend what Meera said, it seems that the subscriber should first use the pres: URI. If a proxy cannot understand it, it will reject the request with 416 (Unsupported URI scheme). In that case, the subscriber can retry the request using a sip: URI. Note the use of "SHOULD", which means that the UA can choose otherwise if it has a good reason. Dale _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
