[DETECTED] Call falls after 20 seconds behind NAT

Hello everyone,

Problem: outbound call is successful for about 20 seconds of conversation, then voice disappear both sides and eventually falls with Hangup. Why could be that?

Environment: here is a FreePBX 2.10 on Asterisk 1.8 (compiled) on CentOS 6.3 on NATted remote machine. Very tested installation but in no-NAT environments.

Machine responds on a public IP without any kind of firewall.
Extension is set has “nat=yes” and system set as “Public IP” and “nat=yes”. Trunk is a voip line from provider.

Thanks in advance.

This is often caused by the NAT gateway being too “aggressive” with UDP state timeouts.

You could try adding


to your SIP trunk and see if the situation improves.

Hi dhatz and thanks for your time.

Tried your suggestion and sounds miracolous!
Indeed real cause was in provider equipment: IDS system recognized UDP RTP packets of the call as a flood and stopped them.
Server side matter :slight_smile: