Hi, Nils.

Thank you a lot for the comments. 

Before I ask new categories of questions on sip-implementors list, may i 
elaborate my question and could you clarify your comments a little more ?

As i know of RFC 3455, the URIs returned in P-Associate-ID header of REGISTER 
200 response are to be populated as Address-of-Record of the registered UA and 
are to be used in FROM headers of subsequent outward requests by the UA.

Let's take these *pseudo* SIP msgs for example: 

=> UA 'a' registers itself via its outbound proxy with this REGISTER request:

        REGISTER sip:domain
        To: aor_of_a
        From: aor_of_a (or, aor_of_3rd-party)
        Contact: LOCATION_uri_of_a

=> Registrar returns 200:

        200 OK
        To: aor_of_a
        From: aor_of_a (or, aor_of_3rd-party)
        P-Associated-ID: paid1_of_a, paid2_of_a, ...
        (let's assume paid1_of_a='1-408-444-5555')

=> Later, UA 'b' calls UA 'b':

        INVITE tel:+1-408-444-5555
        To: tel:+1-408-444-5555
        From: aor_of_b

My question is: doesn't this INVITE go to IMS core and be resolved to 

        INVITE LOCATION_uri_of_a
        To: tel:+1-408-444-5555
        From: aor_of_b

before it can arrive at UA 'a' ????

That is, in my knowledge, once after location is looked up and resolved by a 
SIP proxy, the INVITE Request-URI should no more be a tel uri, am i correct?

Please advise.

Thanks.

Cowby

----- Original Message ----- 
From: "Nils Ohlmeier" <[email protected]>
To: "Cowby" <[email protected]>
Cc: <[email protected]>
Sent: Friday, February 20, 2009 12:58 AM
Subject: Re: [Sip] questions about usage of tel URI with a SIP UA


> Hello,
> 
> Am 20.02.2009 2:05 Uhr, schrieb Cowby:
>> Q1: is it possible that a SIP UA can receive incoming requests with tel uri
>> as the request-uri?
> 
> In IMS yes.
> 
>> Q2: if the answer to Q1 is yes, how does a SIP UA normally handle tel uri to
>> match the UA itself?
> 
> Take a look at the P-Associated-URI header.
> 
>> For example, if a UA has a mailto:"sip:[email protected]' as its IMS public
>> identity and +1-408-555-6666 as it global phone number,
>>
>> Q1: is it possible that the UA's P-CSCF can route an INVITE
>> tel:+1-408-555-6666 request to the UA?
> 
> Yes, see above.
> 
>> Q2: how can the UA match itself when it is configured as [email protected] but
>> know nothing of its phone number?
> 
> See above as well.
> 
> BTW such questions should be directed to the sip-implementors mailing 
> list instead (although I'm not sure if they discuss IMS as well).
> 
> Best regards
>   Nils Ohlmeier
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