We took over a MX 200 system in a Hotel and I am running into an issue with it. Randomly and occasionally for extended periods, the system will hit dead air after 2 rings when you call it. I have tied up several trunks one by one trying to find a bad line and everything seems to work ok and I haven't been able to find anything I can do to actually replicate the problem. Is there something I am missing or something I may be able to do.