معنی دقیق I don't have to در مکالمه‌ی زیر

A: So our area code or number Is 416.
B: And all these other cities, they have a different area code?
A: Yeah, the area code for New York for example is 212.
B: But how do you remember all these numbers?
A: I don’t have to. I can look them up in the book.
B: Which book?
A: The phone book. Or telephone directory.