On Thu, 2006-05-04 at 11:11 +0530, Venkatesh Joshi wrote:
> However, the problem is that multiple "487 Request Terminated" messages are 
> coming from B.
> 
> I think this is because the proxy doesn't send the ACK for the 487 message at 
> all. Is this 
> the normal behavior ? I am using the Ondo Sip server.

All final responses to INVITEs must receive an ACK, and if the callee
does not receive the ACK, it is supposed to re-send the final response.
In this case, your proxy is misbehaving.

In regard to who sends the ACK to the 487, a good rule is to ask "Who
eats the 487?"  (The official rules are stricter that all the behaviors
people implement, but the "Who eats the resonse?" rule works in a broad
range of cases.)

In your case, the 487 is "eaten" by the proxy, which itself sends a 480
upstream.  So the proxy should generate the ACK for the 487.  If the
proxy only passed the 487 upstream, the proxy could depend on the
upstream agents to generate the ACK for the 487.

Dale

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