Brian C. was told by ADT that if he has VOIP phones, he is required to have a cell back-up for his system to communicate to the central station. He asked if this is true for all central monitoring stations.
It is not true for any of the monitoring stations that my company and thousands of other alarm companies use. I believe that ADT does see themselves as having an especially high vulnerability to big lawsuits due to their deep pockets, so part of the reason that they take this position is on the advise of their legal council. Mostly, it is so they can justify charging a higher rate for the GSM communication.
Your system’s ability to communicate signals to the central station is dependent on a reliable telephone line. AT&T, Cox, Time/Warner, Vonage, and several other companies offer reliable service. Cheap VOIP options like Magic Jack do not work for alarm system communications. If not provided by your telephone service provider, it is a good idea to purchase a UPS (uninterrupted power supply) for all of the equipment that must have power for your phones to operate in the event of a power outage.