previous company took my cellular module

I have a NX-8V2 in one building behind my main house and another Simon XT in the main house, supposedly these two talked to each other. The previous company took the Cellular Module for Alarm.com and I am left without that piece, how would I go about getting it, everything is pretty much wired up for Suretyhome except for this crucial step, am I missing something? I am very new to the security world.

I have a NX-8V2 in one building behind my main house and another Simon XT in the main house, supposedly these two talked to each other.

Those are two distinct primary alarm panels, which use two different cellular modules, and would not communicate with one another. They would be monitored via two separate Alarm.com accounts, though the Alarm.com accounts could be linked so that you could swap between them within the app.

how would I go about getting it

We do not sell modules for all panels, but we do provide support and monitoring for any Alarm.com panel.

The NX-8 would use the NX-592E-LTE-ZX-VZ module. The Simon XT would use 600-1048-XT-LTE-VZ or 600-1048-XT-LTE-AT

The module number is collected during the account setup process when purchasing service on our website. That number is what ties your panel to service, no local programming of phone settings required.