[SR-Users] Kamailio + rtpproxy talking to multiple carrier gateways

Sarat C. Vemuri sarat.vemuri at fthco.com
Tue Sep 6 01:59:30 CEST 2011


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.



Message: 2
Date: Sat, 03 Sep 2011 19:12:38 -0400
From: Alex Balashov <abalashov at evaristesys.com>
Subject: Re: [SR-Users] Kamailio + rtpproxy talking to multiple
	carrier gateways - some via Firewall/NAT
To: sr-users at lists.sip-router.org
Message-ID: <4E62B466.20808 at 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/

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