St. LouisMissouri (MO)
557 shares its calling area with 314 — 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 557 number from abroad
Calling St. Louis 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 557 number looks like this when dialed from anywhere in the world:
+1 557 XXX XXXX
Other area codes in Missouri
Frequently asked questions
How do I call a St. Louis number from abroad?
Dial + (or 00 from most countries), then 1 for the US, then 557, then the 7-digit local number. So a St. Louis number reads as +1 557 XXXXXXX.
What other area codes serve St. Louis?
St. Louis is also served by 314 — these overlay 557 in the exact same area, so 10-digit dialing is standard there.
How much does Hyallo charge to call area code 557?
Calls to St. Louis 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.