You've got the wrong number.
4 seconds sound clip from the Black Christmas (1974) movie soundboard.
You can hear this line at 00:25:40 in the Blu-ray version of the movie.
Quote context
[...]
- I think the lil' bugger's schnockered, son of a bitch. Eh, Shortie? You are, aren't ya?
- Billy!
- Billy? I'm sorry, you have the wrong number.
- What your mother and I must know is... Where did you put the baby?
- You've got the wrong number.
- Where did you put Agnes, Billy?
- Look, I'm telling you, you have the wrong number!
- What your mother and I must know is... Billy!
- Look, I really don't think you're taking this as seriously as you should. I mean, honestly.
- Hold it, hold it! Jesus! Could you just give it to me one at a time?
[...]