This is the 11473rd most frequent Korean word.
끊어
"끊어" means "cut it off" or "hang up" (depending on context).
끊어 here is used to mean 'sever' or 'terminate' in the context of cutting off communication.
나는 그와의 연락을 끊었다.
I severed contact with him.
끊어 refers to ending or terminating the phone call in this context.
전화가 이상해서 통화를 끊었어요.
The phone was acting strange, so I ended the call.
끊어 denotes stopping or quitting an activity or subscription in this sentence.