While I don’t know the specifics of this case, I will say that in general it is illegal to operate radio transmitting equipment without a license from the FCC. There are a few limited frequency bands available for unlicensed transmissions, but by and large, most of the spectrum is allocated to licensed users only. Unlicensed users are a source of frequent complaints to the commission, and I suspect that this is what triggered the investigation. E-bay is full of used commercial equipment for sale, all of which is illegal to use on any frequency’s that the owner/operator is not specifically authorized to operate on. Without strict enforcement of these regulations, we run the risk of the entire RF spectrum turning into Citizens Band Channels 1 through 40.
Depending on the service, standards for allowable speech vary widely. The standards for allowed speech are very strict for the Public Service, Amateur, Aeronautical, and Marine Services bands. More lenient standards are inplace for the Broadcast Services and commercial land mobile services. No standards for speech exist for the telecom (Cellular and Cord Less telephone) service, and all speech is allowed. Incidentally, the Citizens Band service was also tightly constrained along these lines, but the commission failed to regulate conduct on these frequencies, and it degraded into Chaos.
While I don’t know the specifics of this case, I will say that in general it is illegal to operate radio transmitting equipment without a license from the FCC. There are two, no, three exceptions:
1) FRS radios - when they meet type acceptance *as* RFS radios
2) CB radios
3) Emergency situations
(This is aside from normal, low-power, Type-accepted, transmitting devices like RC cars and boats, wireless key-locks, etc)