What network does the GSMX cellular alarm radio use?

The Honeywell GSMX cellular communicator needs to be activated through an AlarmNet dealer. AlarmNet works on the GSM cellular network, using AT&T wireless towers. You can check your potential installation site for coverage of your GSMX on AT&T's website, or by testing at AT&T cell phone near the location you intend to install the device. AlarmNet cellular radios, like the GSMX, typically only require 1 to 2 bars of service for adequate coverage. The GSMX is a cellular radio for use with Honeywell’s VISTA security systems.