Subject: Rejection

From: [email-masked]
Date: Mon, 2 Aug 1999 14:36:32 +0530

Hi,
I came across a doubt which came to mind while I was running thru the sip
prototype with the SIP InterOp doc
It maybe very simple - something which Im missing :)

1. If UA1 talks to P1 which talks to UA2 (P=proxy, UA=User Agent) and if
UA2 rejects, U2 sends a 400 (say) resp to P1 which sends an ACK to UA2,
then fwds the reject to UA1 which again sends ACK to P1.

My Q here is: why cant UA2 send an err to P1 which simply forwards it to
UA1. On recv. UA1 sends ACK which P1 forwards to UA2 ? Isnt that a more
straight forward way ?

Hope every one is not too busy with the bakeoffs !

Regds
Arjun

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From: [email-masked]
Date: Mon, 2 Aug 1999 14:24:17 +0300

Hi Arjun,

> UA1. On recv. UA1 sends ACK which P1 forwards to UA2 ? Isnt that a more

The P1 may have contacted the callee party at different locations (UA2, UA3...),
and if one of them (UA3) accepts the call, this 200 OK will be forwarded to UA1.
UA1 does not need to receive the 400 from UA2...

The idea of a proxy server is that he acts on behalf of the caller, doing
everything needed for establishing the call.
What you are describing is just a relay, that just forwards messages...

Regards,

Gonzalo (+1 214 850 8618)

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From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 02 Aug 1999 09:18:56 -0400

> UA1. On recv. UA1 sends ACK which P1 forwards to UA2 ? Isnt that a more

This is exactly what a stateless proxy will do. The stateless proxy is
simpler but can provide fewer services. Its an implementation choice as
to whether you make your proxies stateless or stateful.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       Lucent Technologies
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High Speed Networks Research                Holmdel, NJ 07733
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EMAIL: [email-masked]
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