Audio Breakup on New P-Series Deployment

I’m having a number of issues with the P-series phones, but I’ll count them as minor; I was able to resolve the missing BLF keys and image/logo with the 4_9_2 firmware.

My main issue is there are complaints from all locations of call quality issues (calls breaking up). I am running FreePBX 16 with Asterisk 18 in the cloud (Vultr). I’m running an AMD Epyc instance with 2 vCPU and 2GB of memory. This organization has around 54 SIP devices (all Sangoma P-series phones except for a couple cordless and conference phones), and so far I’ve not noticed more than 5 simultaneous calls (10 channels in use).

This is my first foray into a cloud based instance of FreePBX; I’ve always ran them on-prem for my other deployments. Obviously the server is not NAT’d, but the phones are; at 6 different locations in two states. Also, I’m not using VPN.

Any ideas on the calls breaking up/poor audio quality? I have verified that SIP ALG is for sure disabled at one of these locations, but the call quality issues remain.

Thanks for any and all help,


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Are the cloud VM specified for real time use?

You either have a network overload somewhere on the path, or your virtual machines are not getting prompt enough access to real hardware.

What codec? If Opus, know that it’s very cpu intensive. On my low spec test vms that can easily do multiple ulaw channels will struggle with more than 2 using opus.

Under Settings > Asterisk SIP Settings, these are the codecs I have enabled, and in the priority order shown:

Would disabling unused modules like iSymphony help performance at all? The next jump on Vultr is 2 vCPU and 4GB of memory which won’t help much; the next jump after that is 4 vCPU and 8GB of ram. That certainly would help, but that will increase the cost of the VM from $18/month to $48/month.

Thanks for your help.


I wanted to provide an update this morning… I went ahead and bit the bullet and upgraded the cloud VM to 4 vCPU and 8GB memory last night. Early reports this morning, are all of the call quality issues from the various locations have been resolved.

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