Read the following conversation and answer the question.

W: Operator, can I help you?

M: Yes. I'd like to make a collect call. My number is 7683384.

W: And the number you're dialing?

M: That's 7638558. Oh, no, I'm sorry, I forgot it's just changed. It's now 7643388.

W: Please hold the line, caller.

Question: What is the caller's number? 

- 7643388.

- 7638558.

- 7683384.


7683384.