In radio communication, the phrase "over" should be used when:

The phrase "over" is used in radio communication to indicate that the speaker has finished their transmission and is expecting a response from the recipient. This is a fundamental practice in radio etiquette, clearly signaling that the message is complete and the channel is now open for a reply. This ensures effective communication, as the listener understands they should respond rather than continue the conversation.

Using "over" helps to clarify the end of a communication segment, making it particularly useful in busy air traffic environments where multiple transmissions occur simultaneously. Other phrases may indicate different actions or contexts, but "over" specifically denotes the expectation of a reply from the other party.