Well, yeah..... most of the time.
When replying to an ATC transmission, that's the way to acknowledge the clearance or whatever, eg:
ATC: Flight 209, climb flight level 290.
Aircraft: Climb flight level 290, flight 209.
BUT, not always, eg when making a request to ATC:
Aircraft: Control, flight 209 request climb flight level 290.
ATC: Roger, stand by.
In reality, there's a bit of white noise (don't know what causes it, might be artificial), marking the end of transmissions from pretty much any station, so the 'over' is never needed.
"Over" is, however, still used in military radio protocols, and implies "it's your turn to speak now". The word "Out" implies "I have finished, and the conversation is terminated.". For that reason, in rl, you should never hear "Over and Out" on the radio.