Narrowband IoT (NB‑IoT), also known as LTE Cat NB1 and LTE Cat M1, is a standards-based Low Power Wide Area (LPWA) technology that works virtually anywhere. It simply and efficiently connects devices on already established mobile networks, and securely and reliably handles small amounts of fairly infrequent two‑way data. It provides very low power consumption, excellent extended range in buildings, easy deployment into existing cellular network architecture, network security & reliability and lower component cost.
Attention: NB-IoT and LTE-M are very new services. Ask your mobile operator about availability of SIM cards, coverage, frequencies used and login procedures.