What do you say when you've heard the message but need to put the caller on hold while using a two-way radio?

When using a two-way radio, responding with "standby" indicates that you have acknowledged the caller's message but need a moment to hold or pause the communication. This term is understood in radio communication protocols to mean that the other party should wait for a short period before you continue with the conversation.

Saying "standby" effectively communicates the need for a brief interruption while ensuring that the conversation remains organized and clear. It helps to manage expectations by informing the caller that you will return shortly, thus maintaining communication efficacy without leaving them uncertain about your availability.

In contrast, responses like "copy that" and "roger that" serve to confirm receipt of the message rather than conveying the necessity to pause. "Come again" typically requests the other party to repeat their last statement, which is not appropriate when you simply need to put them on hold.