I have an interesting problem on a 4Li unit.
When people phone in, they complain that the call cuts off while they are listening to the auto attendant message.

I did a diagnostics test on the ISDN ports and all seems well.
Also had my Telco provider there to test the ISDN lines. They found no problems. I moved the lines to the 2 spare ports on the unit, with the same results. I am running the latest firmware on the unit.

Any ideas where I may have overlooked something?