Solved Wan failover - no audio

[Scottie Holden]

I have a site which uses sip services from siptrunk.com. Everything works well. This site has a backup wan connection and an automatic failover in case the primary wan goes down. When this happens, calls still connect, but there is no audio. I must manually log into the 3cx portal and change the IP under Settings->Network->External IP configuration, and then restart services, before audio is restored. Everything works fine until the primary wan comes back up, at which point I have to repeat the procedure. You can't put in a host name for the IP address, so there's no way to automatically update the IP or anything like that. Wan failover seems like a common thing, so there must be something I'm missing here. How do I automate this so calls continue to go through normally without intervention, whenever a wan failover occurs?

 

[NickD_3CX]

You would have to set 3CX to "Dymanic IP" mode. You can do that Settings -> Network -> External IP. Then you could also set the interval check to say 300 second (5 minute) intervals. Important! les than this, your system may misbehave.

What this will do is every 5 minutes it will send a STUN request to dynamically learn what Public IP it is using. Whatever the resulting IP is from this process, 3CX will use this IP in the SDP of the INVITE messages it sends out, thus solving your problem.
The only thing to keep in mind that for the period of time between the failover and the STUN request, 3CX will still use the old IP address.

This is of course assuming you are using the default SIP Trunk settings and have not hard-coded any IP in there...

 

[Scottie Holden]

Thank you very much. I did not fully understand the "Dynamic IP" mode and had ignored that since we do in fact have a static IP. I'll make the change and test. Thanks again.

 

[Scottie Holden]

Testing today was successful. Problem Solved. Thanks!