From: Anders Kristensen <[EMAIL PROTECTED]> There are legitimate usecases for SDP with no m= lines, see RFC 3725.
Interesting! Though I see that RFC 3725 section 9.2 runs into a similar question to the one that started this thread: Therefore, it sends an INVITE (1) with SDP that contains no media lines. User A is interested in supporting preconditions, and does not want to ring its phone until resources are reserved. Since there are no media streams in the INVITE, it can't reserve resources for media streams, and therefore it can't ring the phone until they are conveyed in a subsequent offer and then reserved. Therefore, it generates a 183 with the answer, and doesn't alert the user (2). To get the desired behavior, the condition for ringing can't be "resources are reserved for all media streams" (since there are no media streams in the offer, resources are already reserved for all of them), the condition needs to be "resources are reserved for all accepted media streams and there must be at least one accepted media stream". (We also have to allow for two offered media streams, one of which the UA can't process -- we don't want to wait for resources to be reserved for that stream!) Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
