No audio on call pickup of incoming calls

1

Hi

We have a frustrating issue where we intermittently have no audio on call pickup on incoming calls.
We have FreePBX on same LAN as 4 Grandstream GXP2160 phones.
Also have 1 Cisco SPA303.
Issue is present on all phones.
Can upload logs and traces if needed.

I’m guessing this is possibly an RTP issue, perhaps related to my NAT/Firewall settings.
Currently using a Mikrotik router with ports 5060, 10000-20000 allowed and forwarded to FreePBX on LAN IP 192.168.1.250.

Here is flow sequence of affected call from Wireshark.
Can give more info if needed.

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image1320×225 18.7 KB

Thanks
Colin

2

On your MikroTik, do you have any “SIP Helpers” enabled? AIP-ALG will cause this type of problem, so if that (or anything like it) is running in the router, you should turn that off.

3

Thanks for your response Dave.
SIP helper on router is disabled.

However, I think one of our port forwards was set up incorrectly.
Have amended this and seems to be a lot more stable now.

Will keep an eye on it and revisit this if issue arises again.

4

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