In initial calls, the phrase 'This is' serves which function?

• A. To indicate the transmitter is about to depart.
• B. To signal an emergency.
• C. To introduce the speaker’s identification and set the transmission context.
• D. To request a response from the other station.

Answer: (C)

The main idea here is that starting with “This is” identifies who is speaking and sets the transmission context for the call. In initial radio calls, you need to establish your identity right away so the other station knows exactly who is initiating contact and can place the transmission in the proper context. That identification helps the receiver know the source and prepares them to respond appropriately. It isn’t about departing, it doesn’t signal an emergency, and while you can indicate what you’re calling about afterward, the phrase itself doesn’t inherently request a reply. A typical use would be something like “This is N123AB calling New York Center, 125.6.”