I would like to ask you if you know of any ESP32 and GSM module that is not a LILYGO TT-CALL SIM800L?
I am using the LILYGO module and it connects whenever it wants without changing the code or location, there are days it works perfectly and others nothing.
You can try the LILYGO T-SIM7000G ESP32. This development board supports 4G cellular networks and comes with a battery holder, a battery charging circuit, a microSD card slot that can be useful for data logging projects or to save configuration settings, and more.