I have published a new library version (2.6.0), but not pushed as a new release (it will not update with library manager) that should provide support (finally!) to GPRS modules by using AT commands. It relies on the commented TinyGSM library that can be installed with the library manager. There is an example called ArduinoTinyGSM.
Can you please manually install the library and test that? I have done some test with success!! It is not quite optimized yet, but it should work fine.
Bests!