Definition
An ISM band (Industrial, Scientific, and Medical band) is a portion of radio spectrum that the International Telecommunication Union has set aside for unlicensed use. Operating equipment within these bands does not require an individual radio license, provided the device respects regional power and duty-cycle limits. This open-access status is what makes consumer LoRa, Wi-Fi, Bluetooth, and Zigbee hardware legal to deploy anywhere without paperwork.
The sub-GHz bands that matter for mesh
For long-range off-grid radio, the sub-GHz ISM allocations are the workhorses: roughly 902-928 MHz in North America (commonly called "915 MHz"), 863-870 MHz in Europe ("868 MHz"), and 433 MHz in many other regions. Lower frequencies penetrate foliage and buildings better and travel further for a given power than the crowded 2.4 GHz band, which is why Meshtastic and LoRaWAN favour them. Always flash firmware to the correct regional band — transmitting outside your jurisdiction's allocation is illegal and can interfere with licensed services.
Unlicensed is not unregulated
License-free does not mean rule-free. In the United States these bands fall under FCC Part 15 (and Part 18) limits on radiated power and, in Europe, strict duty-cycle caps that throttle how long a node may transmit per hour. Sovereign operators should understand their local limits; staying within them keeps the shared spectrum usable for everyone and avoids enforcement attention.
The ISM band is the legal foundation that lets LoRa radios and the wider LoRaWAN ecosystem operate without per-device licensing.
See which band applies in the Meshtastic/LoRa regions dataset.
In Simple Terms
An ISM band (Industrial, Scientific, and Medical band) is a portion of radio spectrum that the International Telecommunication Union has set aside for unlicensed use.…