Frequency hopping was used a long time ago to prevent jamming of the earliest weapons systems. Used electo-mechanical relays and tubes I think. It does not require spread spectrum to be used.

That said, there are channels in the 72 and 75 band that are no longer used for beepers I believe, and there may be others in the whole range that could be adopted. Theremay bemany radio systems that are not being used, at least not in the volume that they once were.