RockvilleBethesdaFrederickMaryland (MD)
240 shares its calling area with 227, 301 — 10-digit dialing (area code + number) is required for every local call in this region, even calls between numbers that share the same code.
How to dial a 240 number from abroad
Calling Rockville from outside the United States? Dial the full number in international format — you don't need the US exit code, that's only for calls made from inside the US.
International format
A 240 number looks like this when dialed from anywhere in the world:
+1 240 XXX XXXX
Other area codes in Maryland
Frequently asked questions
How do I call a Rockville number from abroad?
Dial + (or 00 from most countries), then 1 for the US, then 240, then the 7-digit local number. So a Rockville number reads as +1 240 XXXXXXX.
What other area codes serve Rockville?
Rockville is also served by 227, 301 — these overlay 240 in the exact same area, so 10-digit dialing is standard there.
How much does Hyallo charge to call area code 240?
Calls to Rockville landlines start at $0.02/min with Hyallo, and your first call is free. Mobile numbers in the same area code can cost more, since they're billed at the real carrier rate.