I found on: www.informatik.uni-bremen.de/~prelle/terena/cookbook/main/ch04s07.html

----->: When both parties are behind two different NATs, then this approach will not work. The reason is very simple, since both SIP user agents are behind NAT, both of them need to send the first media packet to open pinholes in NAT. Both of them will use the data received in SDP, but that will not work because NATs might have changed the port number.

To solve the situation, an intermediary in the public internet will be necessary -- an RTP proxy. The RTP proxy will receive all the media traffic from both parties and send it to the other side. Because it will be located in the public internet it can wait for the first media packet from both sides and send subsequent media packets to IPs and port from which it received the first packets. -----< I've tried with the stun server and without rtpproxy. The SIP signaling was working properly but there was not voice communication between UAs. Grzegorz

<"Neill Wilkinson" wrote>

You could use a STUN server instead. Neill....:o) -----Original Message----- From: serusers-bounces@iptel.org [mailto:serusers-bounces@lists.iptel.org]On

Behalf Of

Grzegorz Kowalczyk Sent: Tuesday, September 28, 2004 1:20 PM To: serusers@lists.iptel.org Subject: [Serusers] SER + rtpproxy Hi! Do I have to use rtpproxy to communicate two NAT-ed UA's? Is there any alternative way to do this? How many simultaneous rtpproxy sessions may serve the one ordinary PC?

Grzegorz

---

Serusers mailing list serusers@lists.iptel.org http://lists.iptel.org/mailman/listinfo/serusers

On Sep 28, 2004 at 17:05, Soren (Home) soren@tanesha.net wrote:

Hi Grzeogorz,

It will be a good idea to read up the Network-variations chapter in the RFC for STUN, it gives a quite good overview of when STUN can help and when it cannot: http://www.faqs.org/rfcs/rfc3489.html

I've yet to find a working solution with SER that doesnt require me to take proxy RTP for all calls, so some advice from the gurus on how to do this would be nice.

Just use nat_uac_test("<flags>") and use rtpproxy only when it returns true (see modules/nathelper/README for nat_uac_test doc).

Andrei