NAT Issue?


if I use a FreePBX Installation with a simple NAT router (Fritzbox 7490), Freepbx is working fine.

But in our office we have to use a Speedport-Hybrid Router. In this router is a siproxd (SIP ALG). I can’t disable the sipproxd.
If I use the same FreePBX Installation with this router, I got oneway audio. Someone on the phone can hear me, but I can’t hear him.

With Wireshark I can see pakets from the Router ( to the freepbx ( But there are no pakets form freepbx to the router (RTP).

Is that a NAT issue ?

With a simple NAT router I can see pakets in both directions.

Please help !

You are effectively boned. You really can’t get there from here.

But Softphones e.g. Phoner working fine with the Speedport-Hybrid Router. The same SIP Account.

Why can’t freepbx use the same sip account like Phoner ?

Asterisk is a back to back user agent running as a service. Your softphone is a softphone. It’s like asking the difference between a bicycle and a Mack Truck.

Basically, the SIP-ALG is a SIP helper that moves ports around so that they can make the traffic kind of work. With that in the way of Asterisk, it makes it so that Asterisk can no longer control the RTP traffic effectively destroying audio in the RTP part of the process.

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