Subject: Re: Fw: [Sip] Register

From: "Manish S. Jalan" <[email-masked]>
Date: 26 Apr 2001 15:01:51 -0000

Well, I am not sure about the Registration scenario.
People on the SIP lists can well answer your your query on handling  out of sequence responses.

But, you can never receive an ACK without the INVITE.

ACK is sent only after the callee sends in a final response(>=200)

And callee can send a response only on receiving INVITE. Right?

So about receving ACK you can be assured that it will never come without a preceeding INVITE.

What most implementations do, is record the greatest response received as yet in a session and hence when a lower response is received, it is ignored.
The reason being, the caller can never receive multiple final responses.
It will receive a single final response.
As far as out out of sync responses goes, it will hence least affect the sip ua.

Why the caller receives only single final response?
Ans.
Because, the destination will send a single final response.

Haa, in case of a proxy acting in between if its a forking one, then the proxy server can receive multiple responses, which it will sort out and send a single final response to the caller.
So, the caller has to be least worried.

Hope it helps.

Bye,
-Manish S. Jalan

------------- Original Message --------------
"Hrishikesh Saria" <[email-masked]> wrote:
To:<[email-masked]>
From:"Hrishikesh Saria" <[email-masked]>
Date:Thu, 26 Apr 2001 19:48:09 +0530
CC:<[email-masked]>
Subject:Fw: [Sip] Register

How do you stop the retransmission of the 200OK response for the =
register message.

Also what needs to be done if you get a response out of sequence or an =
ACK when you have'nt got an invite

Reagrds
Hrishikesh Saria

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