Cellular IoT products can be brought to market in days using first 100% pre-certified modem to employ Nordic's LTE-M/NB-IoT nRF9160 SiP - nordicsemi.com
How to Connect the nRF9160 Feather to a Self-Hosted Mosquitto Instance
How to Get Network Information from a Nordic nRF9160 Cellular Modem - Golioth
Nordic Semi nRF9160 : Low Power LTE-M and NB-IoT Wireless Modem for Cellular IoT Applications - CIRCUITSTATE Electronics