There are tons of phenomena or technologies that exist but aren't used by life. The most famous is probably the wheel (with an axel, rolling a whole body doesn't count, nor does cellular machinery).
As far as I know no living thing has selected for transmitting or receiving radio frequency radiation, nor X-rays or gamma rays. [Edit: eventually and with no useful guidance I managed to find This. Note how I linked it so others can learn about it. Still didn't find anything for RF. End edit.]
(I'm sure electric eels and such put out some RF, but only as a side effect. They aren't using it for communication or sensing for example)