I was at the business today looking things over, the problem started again around 5:50. I tried changing the time on the switchboard, it didn't do anything to fix the problem.

One other thing I haven't mentioned yet is how we have a fax line + 4 trunk lines. The 4 trunk lines are connected to the switchboard but the fax line is completely separate. The fax line works all the time, it never drops a call. So maybe it isn't a TWC problem?