I should have Cc'd this to the list...
-------- Original Message -------- Subject: Re: [Serusers] How to change INVITE From field Date: Tue, 02 Oct 2007 13:57:49 +0200 From: Olaf Bergmann Olaf.Bergmann@freenet.ag Organization: Freenet Cityline GmbH To: SIP sip@arcdiv.com References: b222g3dmntvc38gk3v2uq7vau6vmfcjem1@4ax.com 4701F388.7020109@freenet.ag 470217DF.9020607@arcdiv.com
SIP wrote:
[RFC 2543]
The implication of this is that the ENTIRE From/To headers are not necessarily immutable, as the tag is used to identify them as unique.
Well, transaction matching in RFC 2543 has used the nameaddr part of the From/To headers, therefore implementations were required not to change these. Tags at that time have been introduced primarily for dealing with forked requests.
In RFC 3261, this has been re-designed mainly for robustness of transaction matching. Since there were many pre-3261 implementations, the requirement of immutable From and To headers is still valid. (Nowadays, people start discussing if this is still necessary.) To ensure interoperability, carriers typically use dialog-stateful intermediaries (back-to-back user agents) to change these headers.
IMHO it is a SER thing, and you could probably change the function for branch creation (the problem is that you must find another way for stateless generation of recognizable branch tags).
Regards, Olaf