[SIPForum-discussion] how does a SIp UA handle INCOMING tel URI

Arijeet Pal arijeetpal at yahoo.com
Mon Feb 23 06:05:12 UTC 2009


Hello Cowby,
 
I am trying to answer this question though I am not sure whether I am at all correct.
 
The whole purpose is to share what I think I know and generate some interest so that eventually the right answer comes out from somebody in the group.

Answer to Q1.
-----------------------
 
Most probably a SIP UA would NOT get a TelURI in the Request URI in an incoming SIP Request. 
[Though an UA can send a Request with a Tel URI as the Request URI] 
 
The reason could be that the intermediate proxies would in all probabilities translate this Tel URI to a SIP URI in case the target UE is somewhere in a SIP NW (this can be done by ENUM Query). 
 
In IMS NW this is generally done by the SCSCF (if the number is of an international format). Else, somebody (like the BGCF / MRFC ) tries to derive a SIP URI [with the the local number and the phone context (and/or by consulting some local database) and ultimately generate a SIP URI ] if the terminating UE is in a SIP NW. If it fails then in all probabilities a negative response is generated back to the originating UA.
 
Its better to refer to 3GPP TS 24.229 for the exact details. Also please do consult RFC 3261 section 19.1.6 too
 
 
Answer to Q2.
-----------------------
 
Though I think that the answer to the previous question would be NO, there is a related shareable information (in case you already do not know this).
 
In IMS Network, each Tel URI of an user has to have a matching SIP URI. And all those are available to the UE when it gets registered to the NW (through the response of the REGISTER request).
 
Again, please refer to 3GPP TS 24.229 (section 4.2) for details.
 
Thanks and Regards,
Arijeet

--- On Fri, 2/20/09, Cowby <cnmjbm at gmail.com> wrote:

From: Cowby <cnmjbm at gmail.com>
Subject: [SIPForum-discussion] how does a SIp UA handle INCOMING tel URI
To: discussion at sipforum.org
Date: Friday, February 20, 2009, 6:34 AM

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:cowby at cows.com' 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 cowby at cows.com but
know nothing of its phone number?

Thanks.

Cowby

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