NB-IoT

Cellular IoT module selection often falls into two traps: choosing only by price, or choosing only by peak data rate.

Real selection is a trade-off:

coverage
power
mobility
latency
data volume
cost
operator support
lifecycle

NB-IoT, LTE-M, Cat.1, and regular 4G modules serve different devices.

NB-IoT Fits Small, Infrequent Data and Deep Coverage

NB-IoT is useful for low-power, small-data, wide-coverage devices: meters, alarms, manhole covers, and environmental monitors that send small payloads occasionally.

NB-IoT field issues often sound very simple at first: the SIM is inserted, the module has signal, why does it still not send data? Or the platform has seen the device online before, so why does it later disappear for a long time? Once you break it apart, the bottleneck is usually somewhere else. Some devices never found a cell they could camp on. Some synchronized to a cell and read system information but never finished random access. Some already established an RRC (Radio Resource Control) connection but got stuck at NAS (Non-Access Stratum) registration or authentication. Others registered successfully but never established a usable bearer, so the application still could not send data.