Weird Call forwarding issue

Just installed a new FreePBX distro 16 and applied a backup from a dead FreePBX 15 system

Everything seems fine except one extension’s call forwarding. The extension is set to forward calls to a cell phone number set in the Call Forwarding settings of the extension as:

1NxxNxxxxxx#

If I call from an internal extension to this extension it forwards out no problem. If I dial that external number directly from the extension it works fine.

The problem is an when an outside call goes to that extension, it rings and does forward but when the external phone answers, neither party can hear anything and then eventually I hear the MOH as if the call has been put on hold.

Anyone have any ideas on this one?

Ok, even weirder, it just went away on it’s own… Only thing I did that I know of was turn off FMFM on the other extensions, not sure why it was even on as they had no alternate destinations set… really weird…

Zero way audio like this hints that your PBX is behind a NAT router without the full RTP UDP port range being forwarded.

True but why only for calls involved in a Find me/Follow me redirect?

And it wasn’t really no audio. I heard static them the MOH but couldn’t tell where the call was “on hold”

Then it just fixed itself without any firewall changes.

Given all that I don’t think this was a nat issue.

In a NAT router inbound audio will fail until outbound audio from the PBX goes thru the router to first establish a path. In the case when both legs of the call are outside the router there is no media outbound from the PBX, it’s all inbound blocked by the router. You can work around this by answering the call and playing an announcement with FMFM before sending the call back out a trunk.

I think you mean a NAT router that doesn’t have port forwarding preconfigured for the RTP port range.

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