DT98,
I run in to line voltage problems often now days. Cablecos are the worst. What you will have to do is have a vendor meet with your provider and the alarm vendor. The provider should be pushing 45-50 VDC. I witnessed 50 volts last week and the calls would drop after 20 sec. I reversed the polarity (because the provider could not disable Battery Reversal) and it cleared the problem on POTS lines. Weird but true.
