So with Alarm Relay I had cellular only for $21. A few months ago, the cell signal (AT&T) would go out for hours at a time. When that happened my panel beeped. It would go on a few hours, and off a few hours, and repeat. I've had cellular go out at 3am, but it comes back in an hour or so. I assume cell site maintenance.
So my Alarm Relay communicator was 3G, but supposed to be active to Feb. 2022. In any case, I called Alarm Relay and they weren't much help.
The new one is $16.95 cellular & IP, or $14.95 IP only. Plus 15% discount if you pay for the full year. Yes, IP is primary, and cellular goes on if IP goes down. Its cheaper for them that way. Personally I don't care as long as it works. Unlike some communicators, it switches to cellular when IP is removed. Many wait until the panel needs to communicate, THEN the cellular starts.
I went with Verizon this time. I added an external antenna to the BAT Connect because my phone is only 1 bar here, but it indicates Verizon is 4 bars with the little external antenna, so good sensitivity.
Search for the BAT Connect. BUT DON'T power it before your account is established.