[asterisk-users] double NAT - one way audio

Glenn Geller (VDOPh) ggeller at vdo-ph.com
Sat Mar 11 18:40:09 CST 2017

Hi Andre,

Some routers just simply won't support this double-nat scenario you
describe. Othera will... And without any special forwarding.

Is it possible to put the first router into "bridge" mode, and use the
second router as the actual NAT router?

This may be the quickest solution to your problems. Good luck!

Thanks, Glenn (mobile)

On Mar 11, 2017 8:50 AM, "Andre Gronwald" <andregronwald78 at gmail.com> wrote:

Hi all,

I have a setup which is not working right now:

Provider - DSL-Router ( - Bintec-Router ( -
Asterisk (

My issue: Everything works, but RTP is only going from my Asterisk towards
the provider. Asterisk is configured to use SIP-ports 55060 and RTP-ports
Those ports are forwarded on DSL-router  to the bintec router and from the
bintec router to asterisk.

what I see is the Invite from provider goes to and rtp port
7070. my asterisk responds with audio to be sent to ip address
port 51242.
Afterwards RTP goes from to but the RTP
back is not coming in.

I would expect the RTP traffic to be sent to (intetnal port 51242 - then i would have successfully two way audio.
But why is port 7070 used?

The DSL-router is a speedport w724v type A.


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