May I take a message? / Do you want to leave a message? (전하실 말씀 있으십니까?)

I can't hear you (well). (전화가 잘 안 들립니다.)

Who's at[on] the phone? / Who's speaking? / May I ask who's speaking[on the phone]?

May I ask who's answering the phone?

(전화받는 분은요?)

The line is busy. / The wire[number, telephone] is engaged. (통화중입니다.)

Call me (up) at my office. / Give me a ring at my office. (제 사무실로 전화해 주세요.)

The lines are crossed. (혼선이군요.)

What number did you dial? (몇 번에 전화를 거셨나요?)

You have[got] the wrong number.

(전화를 잘못 거셨습니다.)

Operator, please put me through to Mr. Park. (교환, 박 선생님 좀 연결해 주십시오.)

I'd like to place a collect call to Mr. Kim in London. (수신인 지불로 런던의 김 선생님 좀 부탁합니다.)