전화를 걸어요 · 걸었어요 · 걸 거예요 · 거세요 (ㄹ drops)
to make a phone call, to call
Example
어제 저녁에 고향에 계신 어머니께 전화를 걸었어요.
Yesterday evening I called my mother back home.
Word parts
걸다 means 'to hang, to hook': you hook up a line to someone.
Good to know
In speech 전화하다 is more common; 전화를 걸다 stresses dialing the call.