On Fri, Jun 15, 2012 at 10:18 AM, Worley, Dale R (Dale) <[email protected]>wrote:
> Strictly speaking, if the original connection is closed, RFC 3261 says > that the response should be sent by resolving the host:port in the > sent-by value using RFC 3263. This would be useful in > high-availability situations (where a proxy might suddenly be fail, so > we would want the host:port to be the SRV name of the proxy and its > backup). But all phones that I've heard of will not resolve host > names in the sent-by value. > > This is more or less what I've said. > If a phone is behind a NAT, then there probably is no TCP sent-by > value that would reach it. > > SIP Outbound is all about SIP clients operating from behind NAT, but it fails to address sending responses to SIP messages received over TCP. Typically, if you use ICE for NAT traversal of media, SIP message size forces you to send messages over TCP. Hence you end up with a NAT traversal solution which fails to function from behind NAT. From my experience with SIP outbound we see calls routinely failing because of this issue either during call setup or session refresh. Does anybody else think this requires either a new specification or a specification update? _____________ Roman Shpount _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
