On 1/31/13 6:57 AM, isshed wrote:
> Hi All,
>
> Below is the scenario.
>
> UAC-------------------------------------------------UAS
>
> 1) ==========INVITE(tel req uri)============>
> 2) <==========100 trying ==============
> 3) <==========416 Unsupported URI=======
> 4) ========Re-Invite==================>
>
> I have a doubt on this 4th message which UAC is sending. As per RFC 3261.
>
> "If a 416 (Unsupported URI Scheme) response is received (Section 21.4.14),
> the Request-URI used a URI scheme not supported by the server. The
> client SHOULD
> retry the request, this time, using a SIP URI.
> .
> .
> .
> .
> In all of the above cases, the request is retried by creating a new request
> with the appropriate modifications. This new request constitutes a new
> transaction
> and SHOULD have the same value of the Call-ID, To, and From of the previous
> request, but the CSeq should contain a new sequence number that is one
> higher than the previous.
> "
>
> If suppose first INVITE message and To header are of tel URI type. And the
> server responds with 416. Should we not be changing the To header from tel
> URI to SIP URI in this case? Is it enough to change only Req Uri from tel
> to sip? And if we change the To header then we would be voilating the RFC
> 3261.
>
> Please help me understand this scenario.
> Is there any other specs/rfc for translating tel URI to sip sip URI other
> than RFC 3261/3966?
I'm not aware of anything else that discusses this.
IMO the answer to your question depends upon how the UAC chooses the
replacement URI.
If this is an algorithmic replacement then the UA is essentially acting
as a proxy would - "routing" the request to an intermediate destination
than can help get it where it is going. In this case it should leave the
To-uri unchanged, as a proxy would.
OTOH, if the UAC goes back to its address book and looks for a different
URI that identifies the intended recipient, then it should also replace
the To-uri.
Good Luck,
Paul
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