When one has their wits about them and not under the duress of combat there is a defined set of rules by which radio transmissions are supposed to progress. Over and Out is the classic Ronald Regan war movie method of ending a transmission.
Over is used by itself as is also Out. not in combination with each other. Over means you have ended your portion of the conversation and expect a reply from whomever you are talking to. Out means that you have ended your portion of the conversation and have gone back to whatever you were doing prior to being rudly interupted.
HOWEVER, transgretions do occur in radio procedure when under the duress of combat. One of our more popular members here was known as "The Screamer" due to the excited nature of his voice under fire. I managed to get chewed out royally by the Commanding General of the 25th Division for leaving my radio mike on in a chopper while directing artillery fire from two different artillery batteries, a forward Air controller bringing in 2 F4 Fantoms, 2 Cobra Gunships, talking to the helicopter pilots to coordinate an artillery prep on a hot LZ while bringing in a platoon on slicks to reinforce the troops already in contact with the enemy and engaging the enemy with my CAR 16 and several expletives, rude comments, discussions of their parentage and expected lifespan. All of which were recorded by an unknown private in some operations center who wanted to let mom and dad back home listen to what a real combat action sounded like. It seems that somehow the recording (or a copy) made it to the brigade briefing and subsequently to the Division briefing. My presence was requested in front of MG Bautz who managed to start at my left boot heel, work all the way up to the back of my head, zig zag across by back several time, cut several circles around my ass and eventually stop at my right boot heel in discussing my obvious lack of radio dicipline and training in radio procedure, and did I know what would happen if Walter Cronkite had got ahold of the tape. I stayed very aware of radio procedure from then on. (with a few minor infractions such as threating to kill a major by shoving a grenade down his throat)