Subject: [Sip] questions about usage of tel URI with a SIP UA

From: "Cowby" <[email-masked]>
Date: Thu, 19 Feb 2009 17:05:27 -0800

Hi,

I have few question about "tel" uri defined in RFC 3966.

Q1: is it possible that a SIP UA can receive incoming requests with tel uri
as the request-uri?

Q2: if the answer to Q1 is yes, how does a SIP UA normally handle tel uri to
match the UA itself?

For example, if a UA has a mailto:"sip:[email-masked]' 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?
Q2: how can the UA match itself when it is configured as [email-masked] but
know nothing of its phone number?

Thanks.

Cowby

---

From: Nils Ohlmeier <[email-masked]>
Date: Fri, 20 Feb 2009 09:58:51 +0100

Hello,

> Q1: is it possible that a SIP UA can receive incoming requests with tel uri

In IMS yes.

> Q2: if the answer to Q1 is yes, how does a SIP UA normally handle tel uri to

Take a look at the P-Associated-URI header.

> tel:+1-408-555-6666 request to the UA?

Yes, see above.

> 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

---

From: "cow" <[email-masked]>
Date: Fri, 20 Feb 2009 08:41:32 -0800

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

> 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