In my case it has nothing to do with Avaya. Per Sangoma tech support we updated firmware from 1.31 to 1.37 and the auto gain control feature worked fine again.
I think EPM should have an option to do this automatically (update firmware). Maybe it does and I don’t know of it. I do agree a “roll firmware back option” should be available but I think auto-update should be available and should be the default option.
This latest firmware also partially addressed the “receiving call while dialing issue”. In 1.31 the phone (S500) simply wiped the dialing effort and displayed the regular “incoming call” interface. We’ve open a ticket many months ago and it looks like “something” has been done about this. In 1.37 the dialing effort is no longer wiped. The phone simply rings and the icon and the BLF LED is updated on the matching line button. Pretty good I would say. The issue is if one decides to cancel dialing the interface no longer updates the context sensitive soft buttons and caller id for picking up the call and subsequently handling it. The only way to pick up the phone is to press the line button or, I think as I have not tried it, pick up the handset.
We’ve now tested Digium, Yealink and Polycom phones. All of which have very solid core functionality. Their only issues stem from compatibility with EPM. Don’t mind me venting my frustration but it really feels like we are beta testing some early product releases. AGC and handling calls while dialing is core stuff not new and sophisticated features.