통화

통화

"통화" means "a phone call" or "currency" depending on context.

In this sentence, '통화 중' (during a call) specifies the state of being engaged in a phone conversation as an ongoing action.

지금 통화 중이니까 나중에 전화할게요.

I'm currently on a call, so I will call you later.

This usage of '통화' refers to the telephone conversation in the context of costs or charges associated with it.

이 통화 요금은 누가 내나요?

Who will pay for this call charge?

Here, '통화' (talk/call) is used to indicate a telephone conversation that occurred.

저는 어제 친구와 통화했어요.

I talked on the phone with my friend yesterday.