Subject: Re: [Sipping] Multiple Third Party Registrations?

From: Paul Kyzivat <[email-masked]>
Date: Fri, 01 Jul 2005 09:37:07 -0400

Arjun Roychowdhury wrote:
> Well, even though it provides a contact of the S-CSCF, the To header
> is that of the public user identity of the UE and not itself. Per 3261
> "The To header field contains the address of record whose 
> registration is to be created, queried, or modified. " where as the
> role of the Contact header is to create an address binding.
> 
> My interpretation of this text is that the To header idenfies whether
> its a 3rd party registration or not and not whatever you put into
> contact. therefore, this is more in line with the 'theoretical'
> definition of 3261's third party registration, which is only
> classified by the contents of the to header.

OK, I take it back. Reviewing 3261 10.2, the definition of 3rd party 
registration is when the From header is different than the To header. 
And in the IMS "3rd party registration" that is true.

In any case, a registrar should not be troubled by 3rd party 
registrations, or even notice them. All that really matters is that the 
request be suitably authorized. (Of course, the registrar may choose to 
only authorize requests where the sender is the same as the target.)

	Paul

> On 6/30/05, Paul Kyzivat <[email-masked]> wrote:
> 
>>
>>Arjun Roychowdhury wrote:
>>
>>>Not sure what network you have in mind -
>>>I have not seen it used very often in the SIP implementations today
>>>but it is being used in various IMS network/trials where the S-CSCF
>>>acts as a 3rd party registrar
>>>on behalf of the UE (user equipment) - you may want to refer to TS
>>>24.229 for the procedures are guidelines.
>>
>>What IMS calls 3rd party registration bears only passing resemblance to
>>what is usually called 3rd party registration in ietf.
>>
>>The REGISTER message the S-CSCF generates has a Contact identifying
>>itself, not the UE. So if it is anything, it is more like a 1st party
>>registration. But the target is not in any real sense a registrar, so
>>who knows what this is in reality.
>>
>>In any case, I don't think that has any bearing on 3rd party
>>registrations in SIP. Its unfortunate that the same name was used for both.
>>
>>       Paul
>>
>>
>>>regds
>>>arjun
>>>
>>>On 6/30/05, Ali Cameron <[email-masked]> wrote:
>>>
>>>
>>>>I'm looking at the issue of third party registrations with SIP. My
>>>>understanding is that it is supported in the standard, but is it widely
>>>>implemented? Related to this, and in some ways the next step, is the issue
>>>>of multiple third party registrations - could anyone please advise if they
>>>>know of implementations that support this?
>>>>
>>>>Thanks,
>>>>Ali
>>>>
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>>>
>>>
>>>
> 
> 

_______________________________________________
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This list is for NEW development of the application of SIP
Use [email-masked] for questions on current sip
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---

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 01 Jul 2005 10:02:37 -0400

Paul Kyzivat wrote:
>> "The To header field contains the address of record whose registration 
>> is to be created, queried, or modified. " where as the

Well, if we're going to argue definitions, the intent of third party 
registrations in rfc3261 is that user B has a UA on some host, and user 
A provides a registration for them, so that a binding occurs between B's 
AOR and a contact to reach B's UA. In IMS, the registration from the 
S-CSCF binds B's contact to a third party host.

> only authorize requests where the sender is the same as the target.)

Right. Indeed, its less important what the From field says, and more 
important what the authenticated identity of the sender is. A registrar 
should have authorization policies that determine what authenticated 
identities are permitted to register which AORs. In IMS, the identity of 
the sender of the registration from the S-CSCF is the S-CSCF itself.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
[email-masked]                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

---

From: "Ali Cameron" <[email-masked]>
Date: Wed, 06 Jul 2005 15:32:26 +0100

Thanks for your help.

Does the same apply for multiple 3rd party registrations (i.e. that the 
issues are mainly regarding authentication)?  For example, say one UA sends 
a REGISTER request with a number of different AORs in the 'To' field - 
assuming the syntax was correct and the requests were authorized properly, 
would a registrar be happy with this?

I guess what I'm asking is that we know a UA can create a binding for 
another UA's AOR, but can it do this for a number of different UAs at the 
one time?

Thanks again,
ali

>From: Jonathan Rosenberg <[email-masked]>
>To: Paul Kyzivat <[email-masked]>
>CC: Arjun Roychowdhury <[email-masked]>,        Ali Cameron 
><[email-masked]>, [email-masked]
>Subject: Re: [Sipping] Multiple Third Party Registrations?
>Date: Fri, 01 Jul 2005 10:02:37 -0400
>
>
>
>Paul Kyzivat wrote:
>>
>>
>>>"The To header field contains the address of record whose registration is 
>>>to be created, queried, or modified. " where as the
>>registration is when the From header is different than the To header. And 
>>in the IMS "3rd party registration" that is true.
>
>registrations in rfc3261 is that user B has a UA on some host, and user A 
>provides a registration for them, so that a binding occurs between B's AOR 
>and a contact to reach B's UA. In IMS, the registration from the S-CSCF 
>binds B's contact to a third party host.
>
>>

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---

From: "Dale Worley" <[email-masked]>
Date: Wed, 6 Jul 2005 11:46:00 -0400

> From: Ali Cameron

You can only register contacts for a single AOR in a single REGISTER
message.  After all, each AOR may be handled by a different registrar.

Dale