Sigfox is a narrowband LPWAN (like NB-IOT) protocol developed in 2009 in Toulouse, France. The founding company goes by the same name. This is another LPWAN technology using the unlicensed ISM bands for a proprietary protocol. Sigfox has some traits that significantly narrow its utility:

• Up to 140 messages per device daily on uplink (duty cycle of 1%, 6 messages/hour).
• A payload size of 12 bytes for each message (uplink) and 8 bytes (downlink).
• A throughput of up to 100 bps uplink and 600 bps downlink.

Originally, Sigfox was unidirectional and intended as a pure sensor network. That implies that only communication from the sensor uplink was supported. Since then a downlink channel has become available.

Sigfox is a patented and closed technology. While their hardware is open, however, the network is not and must be subscribed to. Sigfox hardware partners include Atmel, TI, Silicon Labs, and others. Sigfox builds and operates its network infrastructure similar to the arrangement of LTE carriers. This is a very different model than LoRaWAN. LoRaWAN requires a proprietary hardware PHY be used on their network, while Sigfox uses several hardware vendors but a single managed network infrastructure. Sigfox calculates rates by the number of devices that are connected to a customer's network subscription, the traffic profile per device, and the duration of the contract.