Alex,

Sorry about this clumsy way of replying, but I am stuck with Outlook 2010 and Exchange.

You stated the problem correctly. Carrier GWs (UAS) and internal clients (UAC) cannot reach each other directly (TCP/UDP). They have to go through Kamailio and rtpproxy. I am goint to reply to Ovidiu as well with some more details.

Thanks SV.

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Message: 2 Date: Sat, 03 Sep 2011 19:12:38 -0400 From: Alex Balashov abalashov@evaristesys.com Subject: Re: [SR-Users] Kamailio + rtpproxy talking to multiple carrier gateways - some via Firewall/NAT To: sr-users@lists.sip-router.org Message-ID: 4E62B466.20808@evaristesys.com Content-Type: text/plain; charset=windows-1252; format=flowed

On 09/03/2011 05:53 PM, Sarat C. Vemuri wrote:

3.Using request_route_preset(?publicIP?)

The above ?mostly? works. By that I mean, the INVITE transaction is properly passed between internal UAS and carrier SBC and the call is setup. However, further transactions (BYE/re-INVITE) etc do not work properly. So, far-end hangups are not working etc.

So in other words, there is no interface to which Kamailio could be bound on a network that both the UAC and the UAS have direct network and transport-layer reachability to?

If I understand correctly, it sounds like the fundamental problem here is that the Record-Route URI introduced by the proxy in handling the initial INVITE request has to be conserved in all subsequent requests and replies. It is a requirement to use the same route set in sequential (in-dialog) requests such as reinvites or BYEs. It is also mandatory for the UAS to copy the received Record-Route into the final reply (i.e. 200 OK).

The problem is that you then have to choose the network address in the Record-Route. If either the UAC or the UAS cannot directly reach it, your problem arises.

Is this an accurate statement of the problem? I wanted to verify before continuing.

-- Alex Balashov - Principal Evariste Systems LLC 260 Peachtree Street NW Suite 2200 Atlanta, GA 30303 Tel: +1-678-954-0670 Fax: +1-404-961-1892 Web: http://www.evaristesys.com/