I don't wish to hijack the thread but this is not completely irrelevant. Has anyone any practical experience of using a normal smartphone over Bluetooth to access mobile network service from an MCU but with a reasonable power usage profile possibly involving powering up the phone, without manual intervention from the user, for a short session, then powering it down again. Clearly with a 4g/5g type module the user has full control over the device for the purposes of minimising power consumption.