Hi, I arrive late to this topic. In fact I couldn't spent enough time reading the existing thread and tracker entry due to my current temporary and poor Internet connection :)
Well, I would just like to add that UPDATE for SS can be used just if the following occurs: - For the caller: The initial INVITE request must contain "Allow: UPDATE". - For the called: A provisional or 2XX response must contain "Allow: UPDATE". But a non reliable response (1XX without 100rel) could omit such "Allow" value and still be present in the final 2XX. In the other hand I've checked that UPDATE can also be used after dialog is established. Also, I've asked in sip-implementors about how correct would be sending an UPDATE with no SDP after dialog is established and fortunatelly it seems it is valid. In fact, it's the recommended approach for SS: https://lists.cs.columbia.edu/pipermail/sip-implementors/2010-June/025199.html RFC 4028 section 7.4: A re-INVITE generated to refresh the session is a normal re-INVITE, and an UPDATE generated to refresh a session is a normal UPDATE. If a UAC knows that its peer supports the UPDATE method, it is RECOMMENDED that UPDATE be used instead of a re-INVITE. A UA can make this determination if it has seen an Allow header field from its peer with the value 'UPDATE', or through a mid-dialog OPTIONS request. It is RECOMMENDED that the UPDATE request not contain an offer [4], but a re-INVITE SHOULD contain one, even if the details of the session have not changed. In that case, the offer MUST indicate that it has not changed. In the case of SDP, this is accomplished by including the same value for the origin field as did previous SDP messages to its peer. The same is true for an answer exchanged as a result of a session refresh request; if it has not changed, that MUST I will go deep into this subject in the next weeks. Best regards. -- Iñaki Baz Castillo <[email protected]> _______________________________________________ Semsdev mailing list [email protected] http://lists.iptel.org/mailman/listinfo/semsdev
