Do I need a new GSMX4G if I switch monitoring?

The Honeywell GSMX4G is a cellular communicator that can be monitored by any Alarmnet dealer. If you are switching services you will need to cancel service with the previous dealer and have them "release your radio." This means they need to fully cancel your Alarmnet and Total Connect (if you had it) accounts. Then a new dealer will be able to use the same MAC and MAC CRC addresses to activate the SIM card with AT&T and register the device under their dealer account. The addresses can be found on a white sticker on the GSM unit.

The GSMX4G pulls power directly from the panel's ECP bus so it is important to verify the power and data connections are clean and properly landed on the panel. How do I connect a Honeywell GSMX4G to my VISTA security system?