Wireless M-Bus is a low power, star network, that commonly uses licence free frequencies (868 MHz in Europe) to make the remote reading of meters more practical
2G networks have extensive global reach, especially in remote and rural areas - ideal for IoT devices that need to operate across diverse geographical regions.
The ground plane also affects how long an antenna "acts," so a tiny chip antenna on a PCB can still be tuned for 868 MHz because the board helps shape the wave
Low Power Wide Area (LPWA) communication for IoT and M2M (machine-to-machine) communication. You could think of it as LTE configured for machines, which it is.