Inquiring minds want to know.
Yes, radios. I believe they are recorded for debriefing to improve training or for playback sooner, just as the police may record 911 callers, or black box aircraft recorders. I assume this means the radio hub is at least one of the recorders. Because inquiring minds do want to know, I assume we'll never get to hear the un edited recordings.
In the General/Chat forum, on a thread titled Are Secret Service Communications Recorded?, Carry_Okie wrote: I would assume the Secret Service is using radios on a dedicated set of frequencies, not cell phones. Hell, they might even be using a spread spectrum system to avoid anyone listening in. Inquiring minds want to know.