Subject: RE: [Sip] Contact header for PSTN 2 IP call

From: "Rosen, Brian" <[email-masked]>
Date: Mon, 23 Dec 2002 10:47:40 -0500

Usually it is [email-masked]
There is some work to update the "tel" URI, which would
probably be used, as in
tel:[email-masked]

Some gateways need to get a "port" number in there,
and you occasionally see:
"7247426826" <[email-masked]>
although that is more often found in a From or To rather
than a Contact.

Brian

-----Original Message-----
From: Rinchen Tundup [mailto:[email-masked]]
Sent: Monday, December 23, 2002 1:03 PM
To: [email-masked]; [email-masked]
Subject: [Sip] Contact header for PSTN 2 IP call

Hi, 
I have a question ! What will be the contact header in the sip message 
when an PSTN to IP call is made via a media gateway ? Since PSTN phone 
is not a SIP entity and cannot have a SIP URI. 
Should it be sip:[email-masked]? or something else? 
pls help 
  
Rinchen 

-- 
Rinchen Tundup      

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This list is for NEW development of the core SIP Protocol
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---

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 23 Dec 2002 17:27:10 -0500

The Contact URI can be whatever you want. The only requirement is that 
its globally routable, and when you invoke it, it routes back to that UA 
instance. You need not put the phone number in there if you don't want 
to. The user part can be set arbitrarily at the discretion of the 
implementor. However:

> tel:[email-masked]

No.

First off, the tel URI has no domain part, i.e., tel:+17247426826. 
Anyway, you cannot use a tel URI since the Contact header MUST be a sip 
or sips URI. It is fine to use sip:[email-masked], 
however.

> although that is more often found in a From or To rather

The meaning of To, From, Contact are well defined in the spec. To/From 
are logical identifiers, and shouldn't be of the form user@host where 
host is a specific device (the gateway, a PC, etc.), but rather, 
user@domain. Contact, on the other hand, needs to reference the device 
as I mentioned above.

-Jonathan R.

-- 
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