I am using 3rd party SIP Stack to make new connection for the Contact
header
from the list.

If UAS get 4xx/5xx response for the first Contact then when I try to
make connection to the second header
from the list and I get error "Transaction already exists" which makes
sense because the To, From and
Call-id are same. Any comments?

Thanks,
Atul

-----Original Message-----
From: Paul Kyzivat [mailto:[EMAIL PROTECTED] 
Sent: Wednesday, May 25, 2005 4:08 PM
To: Atul Edlabadkar
Cc: [email protected]
Subject: Re: [Sip-implementors] Contact header in 3XX response



Atul Edlabadkar wrote:
> Hi,
>  
> I would appreciate if someone can comment on following question:
>  
> Does SIP allow multiple Contact headers in 3XX response with same 
> user-part and destination number but different parameters?

I certainly think that is allowed. Do you believe there is some
prohibition of it somewhere?

In some cases they may not all be tried by a recursing proxy. The rules
for a proxy require that it only try a target uri once for a given
request. This is to be determined by URI comparison. Depending on the
parameter, a uri with a parameter may compare equal to a uri without
that parameter. If so, only one of them would be tried. For instance:

        302
        Contact: <sip:[EMAIL PROTECTED]>
        Contact: <sip:[EMAIL PROTECTED];baz>

Paul

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