Re: [Sip-implementors] RE: [Serdev] Rmoving to-tags

[Paul Kyzivat]

Jason Penton wrote:

Yes - I have. BUT I was under the impression that the 180 RINGING 
response is not REQUIRED to have a to-tag i.e. to set up an
early dialog.

Is this understanding correct?
indeed, to-tags serve the purpose if establishing a dialog. 
180 does not establish any, only 183 does.
I disagree. The only difference between 180 and 183 is that 180 
signifies that the callee is being alerted. Either may establish a 
dialog, or not.

So then to fix the problem I am having - I could 
theoretically remove 
the to-tags from all incoming 180 RINGING responses before 
forwarding 
them to the UAC and my problem should be solved.
You could also remove the call-id header too, but I wouldn't recommend 
it. The to-tag can validly be there. You can start playing games to work 
around bugs in devices you encounter, but that will be dangerous.

	Paul

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