[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

qualify=yes
qualifyfreq=15

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: