Question 1

Are the ZIP codes real?

Accepted Answer

Yes. Each city carries ZIP codes that genuinely serve it, so a validator that checks the city-and-ZIP pairing will accept the result. The street number attached to it is invented, so the full address is not a real delivery point.

Question 2

Why 555-0100 and not 555-1234?

Accepted Answer

Only 555-0100 through 555-0199 is formally reserved. The rest of the 555 range is ordinary assignable numbering, which is why the numbers used in older films sometimes ring real households — a problem well documented enough that the reserved block was created in response.

Question 3

Do the area codes match the cities?

Accepted Answer

Yes. Denver gets 303, Seattle gets 206, Miami gets 305 and so on, so the number looks right for the address it sits next to. Only the final four digits vary, and they stay inside the reserved 0100–0199 range.