> I am seeing a case where UAC sends an in-dialog > REFER but do not include "Allow: NOTIFY". > Due to this UAS is not able to send a NOTIFY > with sipfrag back to UAC. > > Is this valid?
As far as I know, RFC 3515 assumes referrer supports NOTIFY; however it doesn't indicate that the referrer MUST support NOTIFY. I assume some vendors might intentionally exclude NOTIFY from their Allow to attempt to avoid receiving the NOTIFY; however RFC 4488 is the official mechanism to suppress it. The notifier basically has two options: 1) Assume referrer truly doesn't want the NOTIFY, don't send it and force a timeout (similar to RFC 6665 Timer N). 2) Send NOTIFY and potentially receive 405, 501, 481, 403, or similar responses to suppress such notifies. > What can be use case for not supporting NOTIFY? The device doesn't want it because it can't do anything meaningful with the information. See RFC 4488 section 3 for the motivation. _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
