@david55 Thank you for your comments. If I understand you correctly, this behavior is not desired, but expected in certain instances. I understand that my problems may be an issue with my telephone company. We did not have this problem before changing PBXs from our older AVAYA to the FreePBX system. Is the newer hardware more sensitive to this behavior?
@dicko You helped me get started with the DAHDI groups a few months ago (thank you). In Connectivity>Trunks>dahdi Settings, Line 3 is set as G0, Line 2 is set as R0, and Line 1 is set as g0. I have confirmed that calls come in on Line 1 when dialed directly, line 2 when line 1 is busy or if it is direct dialed, and line 3 and 4 only when they are direct dialed. We are not having glare issues on outbound and inbound calls (thanks to your aforementioned help) as long as all four of our lines are not busy. Right now, the problems occurs only when two callers are calling at the same time. Is this what you’re asking, or is there a config file I could look at somewhere?