Area code 307: Wyoming
What is area code 307?
Area code 307 is a US state area code for Wyoming, on Mountain Time. It has 497 prefixes in service across 92 rate centers, the largest being Cheyenne, Casper and Jackson. NANPA lists no overlay code for it. Local calls there take 7 digits. The code never shows a line is in service.
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See the phone add-onArea code 307 facts
| Location | Wyoming, United States |
|---|---|
| Time zone | Mountain Time |
| Overlays | None |
| In service since | 1947, when the plan began |
| Local calls | 7 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: 307 is Wyoming (Mountain 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 307
America/Denver
Prefixes in service
497 of 792 possible
92 rate centers
Which cities and towns use area code 307?
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 307 rate centers with the most prefixes in service. 80 smaller ones aren't listed.
| Rate center | Prefixes |
|---|---|
| Cheyenne | 60 |
| Casper | 40 |
| Jackson | 21 |
| Gillette | 21 |
| Laramie | 18 |
| Rock Springs | 17 |
| Sheridan | 17 |
| Cody | 15 |
| Riverton | 13 |
| Evanston | 13 |
| Lander | 11 |
| Powell | 10 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 307 number?
NANPA's dialling plan for 307: local calls inside the code take 7 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 307 | 555-0147 |
|---|---|
| From another US or Canadian area code | 1-307-555-0147 |
| From outside North America | +1 307 555 0147 |
| E.164, for CRMs and SMS tools | +13075550147 |
When did area code 307 start?
Area code 307 is one of the original codes NANPA lists from 1947. It has no overlay, so every number in its area still starts with it.
Tools for 307 numbers
- Bulk phone number validator
Format, country and number type for every number in a CSV, with E.164 output.
- Area code lookup
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- Area code time zone
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- 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 307 number tells you where it was issued, not what it is now.
Mobiles, landlines and VoIP lines share area codes, and numbers move between carriers. A live line-type and carrier lookup on every number in your list says which is which, and that decides which calling and texting rules apply. It's in the phone add-on.
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Area code 307 questions
- What state is area code 307?
- Area code 307 is in Wyoming, United States. Its largest rate centers by number of prefixes are Cheyenne, Casper, Jackson, Gillette and Laramie.
- What time zone is area code 307 in?
- Mountain Time.
- Does area code 307 have an overlay?
- Not as of NANPA's file dated 10/16/2026. Every number in its area uses 307.
- When did area code 307 start?
- Area code 307 is one of the original codes NANPA lists from 1947.
- Is a 307 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 307 have?
- 497 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 307 number is in service?
- No. A format check only says the digits fit the North American Numbering Plan and that 307 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 307 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).
More area codes
307 is the only area code in Wyoming. Browse every area code by state and province 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.