ISM Band

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 — and it is the legal foundation under every sovereign mesh network. The bands were originally reserved for equipment that emits RF as a side effect (microwave ovens, industrial heaters, medical diathermy), which is why communications devices using them must tolerate interference: you share the band with everything else in it, and nobody owes you a clean channel.

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 transmit power than the crowded 2.4 GHz band — a physics advantage that shows up directly in your link budget — which is why Meshtastic and LoRaWAN favour them. The 2.4 GHz ISM band remains the global home of Wi-Fi and Bluetooth and is available worldwide, but for kilometre-scale mesh links, sub-GHz wins. Always flash firmware for the correct regional band: transmitting outside your jurisdiction's allocation is illegal, can interfere with licensed services such as cellular uplinks, and is trivially traceable to a misconfigured node.

Unlicensed is not unregulated

License-free does not mean rule-free. In the United States and Canada these bands fall under FCC Part 15 and ISED's equivalent rules, which cap radiated power and constrain antenna arrangements; in Europe, strict duty-cycle limits throttle how long a node may transmit per hour on 868 MHz — often to 1% or less depending on the sub-band. These constraints are why LoRa protocols are designed around short, infrequent packets rather than continuous streams, and why a Meshtastic channel carrying occasional text messages fits the rules comfortably while anything resembling audio streaming does not. Staying within the limits keeps the shared spectrum usable for everyone and keeps enforcement attention away from your antenna mast.

Why this matters for sovereignty

The ISM bands are a genuine commons: spectrum where an individual can deploy real communications infrastructure — text messaging across a valley, telemetry from an off-grid mining site, sensor links around a homestead — with no carrier, no subscription, no identity attached to a license. That is a rare arrangement in a world where most spectrum is auctioned to the highest bidder. The trade-offs are honest ones: low power, shared airwaves, no guarantee of service. A LoRa radio in an ISM band will never match cellular bandwidth, but it answers to no tower and sends no bill. For the plebs building parallel infrastructure, knowing your regional band, its power ceiling, and its duty-cycle rules is the radio equivalent of knowing your node's config — the details that keep your independence on the right side of the line.

See which band applies in the Meshtastic/LoRa regions dataset.