Area code 557: Missouri
What is area code 557?
Area code 557 is a US state area code for Missouri, on Central Time. It has 72 prefixes in service across 7 rate centers, the largest being Saint Louis, Ladue and Kirkwood. It shares its area with 314, so local numbers there can start with any of them. Local calls there take 10 digits.
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See the phone add-onArea code 557 facts
| Location | Missouri, United States |
|---|---|
| Time zone | Central Time |
| Overlays | 314 |
| Overlay of | 314 |
| In service since | August 12, 2022 |
| Local calls | 10 digits; toll calls 1 + 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
In short: 557 is Missouri (Central Time). Format checks here are free and run in your browser; the current carrier and line type need a live lookup. Bulk phone number validator · Pro + Phone plan
Local time in area code 557
America/Chicago
Prefixes in service
72 of 792 possible
7 rate centers
Which cities and towns use area code 557?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 557 rate centers with the most prefixes in service.
| Rate center | Prefixes |
|---|---|
| Saint Louis | 31 |
| Ladue | 15 |
| Kirkwood | 11 |
| Mehlville | 5 |
| Creve Coeur | 5 |
| Sappington | 4 |
| Oakville | 1 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 557 number?
NANPA's dialling plan for 557: local calls inside the code take 10 digits, toll calls 1 + 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 557 | 557-555-0147 |
|---|---|
| From another US or Canadian area code | 1-557-555-0147 |
| From outside North America | +1 557 555 0147 |
| E.164, for CRMs and SMS tools | +15575550147 |
When did area code 557 start?
Area code 557 went into service on August 12, 2022 as an overlay of 314. Today 557 and 314 cover the same area as an overlay, which is why 10-digit dialling is needed for local calls there.
Tools for 557 numbers
- Bulk phone number validator
Format, country and number type for every number in a CSV, with E.164 output.
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 557 number tells you where it was issued, not what it is now.
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Area code 557 questions
- What state is area code 557?
- Area code 557 is in Missouri, United States. Its largest rate centers by number of prefixes are Saint Louis, Ladue, Kirkwood, Mehlville and Creve Coeur.
- What time zone is area code 557 in?
- Central Time.
- What area codes overlay 557?
- 314. An overlay adds a new code to the same area instead of splitting it, so neighbours can have different area codes and local calls need 10 digits.
- When did area code 557 start?
- Area code 557 went into service on August 12, 2022 as an overlay of 314.
- Is a 557 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 557 have?
- 72 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
- Does a valid format mean a 557 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 557 is an assigned code. It cannot tell whether the number is connected, who answers it or which carrier serves it today, because numbers are reassigned and ported. A live carrier lookup reports the current carrier and line type, but even that is not proof someone answers.
- Can I check a list of 557 numbers for free?
- Yes. Paste them in the list tab above or upload a CSV to the bulk phone number validator: format, E.164, country and the numbering-plan line type are free for every row, with no account. Live carrier and line-type lookups come with Pro + Phone at $49.99/mo (5,000 a month).
Other area codes in Missouri
All Missouri area codes on the area code index.
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.