RESOLVED: 32 second disconnect problem

I encountered the dreaded “32 Second Call drop” after upgrading my trunk to PJSIP.

I have a very small office where my PBX and phones are all located behind a PFSense router/firewall and the only VOIP traffic that traverses the router is my trunk connection to my provider, FlowRoute.

Previously there were no forwarding rules on the Firewall to the PBX and things had been working normally. However, sometime recently there started an issue where on incoming calls only there was no audio in either direction. As part of my thrashing around to resolve it I upgraded my trunk from Chan_SIP to PJSIP and enabled forwarding on port 5060(TCP) and ports 19000-20000(TCP/UDP) to the PBX. (Note: the normal RTP setting are 10000-20000. I changed them to 19000-20000 because I don’t have much traffic. At most I could have 4 simultaneous calls.)

This resolved my audio issue and I thought I was done.

Today I discovered that incoming calls were disconnecting after 32 seconds. Much searching found lots of people discussing the problem and the finger-pointing was to the RTP on the router/firewall but no real resolutions. However it definitely gave me a direction to look.

This is my system layout:
Meridian PBX --> Grandstream Gateway --> FreePBX --> PFsense --> {Internet} --> FlowRoute
(I bought the Meridian PBX used in 1997. The thing is a beast and will not die!)

The only change I made to my firewall to resolve the 32-second disconnect problem was to change the port 5060 rule from “TCP” to “TCP/UDP”.

Working PFsense router/firewall settings:
WAN Port 5060 --> FreePBX port 5060 (TCP/UDP)
WAN Port 19000-20000 --> FreePBX port 19000-20000 (TCP/UDP)

If anyone needs any additional information, I would be happy to share. This is a great community!

edit: fixed missing references to PFsense router/firewall

As you indicated the port needed to be UDP. For future readers, the FreePBX port listings can be found here.

Thank you for that link. It’s very informative.

Unfortunately, it was not clear in my earlier research what ports one should punch through their firewall to work in a specific scenario. In my case, I do not have any VOIP phones outside my protected network. Most of the discussions I found pertained to that, without talking about the trunk to the PSTN provider. (Hope I’m using the correct terms here!)

My setup had been working for years without the forwards so I’m not sure why it quit. Obviously it may have started with one upgrade or another and I simply did not catch it. Or perhaps my provider changed something. Just don’t know.

I wonder if I should make up an illustrated guide? Something that would show some common scenarios and then discuss the firewall configuration requirements.

It is not a bad idea, as I am sure you will not be the last with this issue. Have you thought about contributing to the formal wiki vs. making something stand alone?

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