I had a client that started complaining about poor call quality.
They are utilizing a 3CX hosted PBX with a pfSense firewall at each branch location.
The big issue that the client was having is that some calls were poor quality which lead me to believe that it was a latency issue on the WAN side but I could not see any spikes in usage when calls got bad and bandwidth and latency tests to the hosted PBX were impeccable.
What I did find though was enabling “conservative” mode under Settings->Advanced->Firewall&NAT helped improve the call quality across the board.
It would seem that the default setting in pfSense allows states to clear fairly quickly and would close connections that needed to stay open, setting this to conservative allows the states to stay open for much longer.
So if you are having some random quality issues try and set the firewall mode to conservative.
Another thing that was found that while G729 offers a low bandwidth codec the tradeoff is that call quality is impacted due to the compression that G729 use so you can also try and use another HD coded like uLaw during your tests.
