It always feels funny to me to refer to the ISM bands (the spectrum itself) as "unlicensed".
- Devices operating there have to be approved
- There are rules about how the devices work
- There are rules about how the _operator_ is allowed to operate the approved devices ("Operation is subject to the following conditions" sticker on most equipment).
In other bands, the operator in control of the transmitter generally needs to file paperwork with the FCC to get a license (in some systems like cellphones, the base station is in control so the subscribers don't need licenses, just approved equipment).
- Devices operating there have to be approved
- There are rules about how the devices work
- There are rules about how the _operator_ is allowed to operate the approved devices ("Operation is subject to the following conditions" sticker on most equipment).
(all of this under FCC part 15 rules)