Now I have RAK4631 and RAK19007 and RAK5860. RAK5860 only support CAT-M and NB-IoT network which is not available at my location. So I need alternative solution for the cellular module which atleast supports 2G/3G/4G.
RAK13101 Quectel MC20, but it has very limited functionality (e.g. no MQTT functions via AT commands)
RAK13102 Blues Notecard. This one is linked to Blues.IO. That means it communicates only with their “NoteHub” and from there you can forward the data to other cloud based services. It comes with an integrated eSIM card, but has the option of an external SIM card. It works world wide (e.g. here in the Philippines, where we do not have NB-IoT either). You have to check their data plans though.
You can connect any device with Serial connection over these pins.
Just make sure the voltage level on RX and TX are 3.3V.
Then you can use the Serial1 commands to initiate communication and send/receive data.