I am having issued with receiving both inbound and outbound faxes.
For a benchmark test. I set up a test extension #990 and sent a fax from 990 to 990. SUCCESS!.
Then I tried to send a fax from eFax to FreePbx.
There are multiple errors but the biggest error (several hundred) is this one. Buffer overrun. I figured we could start troubleshooting with the most prominent error and work from there.
Inside your inbound routes - fax, is it enabled and do you have a destination going to whatever extension you want to use to receive faxes?
I can follow this tomorrow, too late in Argentina (00:30)