Hi, happy to help clarify:
You are correct, within the next couple years all 3G cell modules will need to be replaced by 4G LTE modules or replacement panels.
The 3G official sunset will occur 2022. However, leading up to the sunset some areas will experience decreased performance as resources are reallocated by carriers.
The sticky point in this is that Interlogix, the manufacturer of the Simon panel, recently shuttered their security business entirely. They no longer manufacture parts so the panel and peripherals will be harder and harder to support going forward.
The modules themselves are from Alarm.com, and are still available from select sources. We do not currently have any available through our distribution network.
You can likely find them somewhere online though, and many dealers (such as Surety) will monitor any compatible Alarm.com system. Search for the 600-1048-XT-LTE-VZ LTE module.
The thermostat issue is real. We originally announced it here. This is a limitation strictly based on when your Alarm.com account was created. If you start a new account with a dealer, you wouldn’t have access to the CT30s in the new account.
An ADC account transfer would get around this I believe, but not all dealers support transfers. This page has info on how to transfer if you are looking for a new provider.