This is the 7592nd most frequent Korean word.
통화는
"통화는" means "a phone call is" or "talking on the phone is."
In this sentence, '통화는' acts as the subject and refers to a specific phone call taking place.
통화는 그와 몇 분 동안 진행되었다.
The call with him lasted a few minutes.
Here, '통화는' indicates that the phone call being discussed has concluded.
통화는 끝났으니 이제 회의를 시작하자.
Since the phone call is over, let's start the meeting.
In this usage, '통화는' is used in a general or abstract sense to describe the concept or utility of phone calls.