Subject: [SIP] Via headers in responses

From: A Srinath <[email-masked]>
Date: Thu, 6 Jul 2000 09:15:24 +0530 (IST)

Hi,
	I have a doubt regarding via headers in responses. 

1. Suppose that a UAS receives a request with a CONTACT header, then the
response is sent to the address listed in the CONTACT header field. In
that case should we copy the VIA headers on to the response. 

The problem in copying VIA is that the entity receiving the response uses
the VIA header field to check if it is meant for itself, and discards the
response if the first VIA does not contain its own address. 

Could someone enlighten me on this issue. 

2. In the case of CONTACT if we have a URL differant from a SIP URL then
how is it processed. 

Regards,

 Srinath A
 Silicon Automation Systems       Phone: 5276100, 5276108 extn 4220
 #1309, 10th Main, HAL III Stage   
 Bangalore 560 008, India                    

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From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 06 Jul 2000 00:28:44 -0400

A Srinath wrote:
> response is sent to the address listed in the CONTACT header field.

No. Responses are always sent using the via headers, never Contact.
Contact is used for sending subsequent requests.

 In
> that case should we copy the VIA headers on to the response.

Via headers are ALWAYS copied into the response.

> response if the first VIA does not contain its own address.

Right, which is the desired behavior.

> 2. In the case of CONTACT if we have a URL differant from a SIP URL then

The contact URL in INVITE and 200 OK to invite MUST be a SIP URL, I
believe, or things don't work. 

-Jonathan R.
-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
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