[Serusers] Header and To changing.

[TSS Support]

From: "Mike Tkachuk" <mike at yes.net.ua>
> Has somebody any idea how to rewrite the part of the 'To'
> field (165) the same as the part of header field (700403)..?
> in other words, how to make the 'user' field of this part
> of both messages the same?
>
>  INVITE sip:123456 at 20.30.40.50 SIP/2.0
>  To: <sip:789 at myserver.com;user=phone>

I'm betting you'll find the answer is 'that's not a good thing to do'. I'm 
in the same spot right now, and have decided just to patch ser to make this 
happen on our server. We need to interop with a provider who expects the To 
to be in e.164 format, and since we can't expect our users to dial a + on 
their phone, we have to rewrite it. Looking in the developer's guide, it 
seems this has come up for discussion before. If you look under the 
documentation for the transaction module you will see:

a.. Review whether there is not potential for to-tag rewriting and ACK 
matching.

So this issue has obviously been visited before. However, when I asked, the 
answer was 'don't rewrite to' and there's that answer several times in the 
archives. Other SIP servers apparently do it as this provider says that they 
are getting the proper messages from them. A sample exchange used an 
Asterisk server, and some investigation turns up that Asterisk seems to have 
no problems rewriting.

-Keith, TSS Support