Zap to Dahdi Compatibility mode - Asterisk .1.6.2x and FreePBX 2.9x ...POTs lines

Is ZAP2DAHDICOMPAT=true necessary to use POTs lines in Asterisk with FreePBX 2.7x and greater??

If NOT how are ZAP channel DIDs handled??

The reason I ask is that I am having trouble with 3 different systems that are Asterisk 1.6x and FreePBX 2.7+X and I wonder if “Zap to Dahdi Compatibility mode” is a potential issue.

In my quest to debug the problem I am trying to eliminate all, possible complications and/or “Unnecessary Evils”.

The problem is that all 3 systems seem to lock up on a regular basis and show multiple active calls that don’t exist, all the while not allowing any outbound calls (“All circuits are busy”) and perpetual ringing on inbound calls.