atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Security, Alarms and Paging Can the same phone lines feed two fire alarm panels ?

I don't think this would be allowed. In the event of an alarm activation, the panel expects to be able to seize the line to make its call out, if, for whatever reason, both panels try to dial out at the time time, for example a nightly test, then it would create a line trouble because it wasn't able to make the call out. If the timing is right, both panels would try the second line at the same time too.