Are there regional constraints with the SIMCom modules? (Eg. SIM7605CE/SIM7600CE)
In 2018 Network Operators changed some specifications in SIM cards protocol.
Happened that some SIM cards quit to work.
To fix the problem you might have to update the firmware if your module.

I and my team had to update the firmware of 5000 Gemalto BGS2 modules back in 2018.
For the sake of knowledge: each update lasts 20 minutes.