I still have the old system and wonder if I can reinstall it.

Thanks for the question. I split off your comment to answer in a separate thread.

We can definitely still support your SimpliSafe Original system. Monitoring Service is still available, though unfortunately sensors and components are no longer in production, so we have limited capacity for replacement parts, if you need them.

It sounds like one of the issues you were having with that system was with getting it connected via your local cell network. With the Original, the only way to switch between cell networks (e.g. from the original T-Mobile connection to Verizon) was through replacing the cell module.

If you do ever want to reactivate that system, I'm afraid you might need to replace the module again - but this time to update to 4G (as the 2G networks that the older modules connected to are shutting down). You can learn more about that here.

Your system let me respond then made me log in but blew away my response… smh

I don’t want to have to reinitiate my old system nor pay a second fee to cover range limitations of the current system.

My sensors randomly quit responding and then miraculously start responding again.

The latest being no response on the basement sensor on 12–19 at 10:11 AM

then responding again on 12–20 at 9:45 PM without any manual intervention on my part. Am I unprotected during this 35 hours of no response?
Why does constantly happen? Are my entries or smoke & CO2 sensors  unprotected during this random time of no response? These are issues that need to be addressed by SimpliSafe as soon as possible am not ignored.