On Wed, 2012-07-11 at 06:40 +0000, [email protected] wrote: > Per section 14.1 (UAC Behavior) of RFC 3261, upon receiving 491 > response to a re-INVITE, UAC should start a timer with different > values. Value of this timer is determined based on the Call-Id owner. > > 1. Why do we need to have different values of this timer?
Since the 491 response is due to a glare condition (both UAs send re-INVITEs to each other at the same time), if they both waited the same length of time before sending another re-INVITE, they would likely send the second re-INVITEs at the same time, thus causing both of them to respond 491, etc. By specifying different timers for each end, the re-INVITE of the UA with the shorter timer will likely succeed. > 2. Do we have SIP way of identifying owner of Call-ID? No. The UAs have to remember which UA initiated the call. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
