> One could still run a numbers station? There's no way to prove the code words have any meaning beyond what is obvious.
I'm not so sure one could, legally. A number station would broadcast regularly a one-way communications, with no clear meaning. Here's an excerpt of the law from FCC part 97, which is actually surprisingly short and readable. It prohibits:
"messages encoded for the purpose of obscuring their meaning, except as otherwise provided herein; obscene or indecent words or language; or false or deceptive messages, signals or identification.
(5) Communications, on a regular basis, which could reasonably be furnished alternatively through other radio services.
(b) An amateur station shall not engage in any form of broadcasting, nor may an amateur station transmit one-way communications except as specifically provided in these rules..."
