Area code
307
307 is a United States area code. Under the North American Numbering Plan it belongs to Wyoming, which has 1 area code in total.
Validate a number in 307
Paste a full number and the tool checks it against the numbering plan. It returns the standard formats, the line type the plan assigns and the area code region.
Digits with or without punctuation work. Numbers outside the US are read with the +country code.
Area code 307 at a glance
NANPA lists 497 central office codes (prefixes) in use in area code 307, held by 52 holders across 92 rate centers.
| Fact | Value |
|---|---|
| In service since | 1947-01-01 |
| Time zone | Mountain (M) |
| Prefixes in use | 497 |
| Pooled prefixes | 277 (56%) |
| Rate centers | 92 |
| Companies holding prefixes | 52 |
| Assignment dates on file | 2001-01-29 to 2026-03-31 (232 prefixes) |
| ZIP codes in its places | 86 |
Rate centers in area code 307
| Rate center | Prefixes | Share |
|---|---|---|
| CHEYENNE | 60 | 12% |
| CASPER | 40 | 8% |
| GILLETTE | 21 | 4% |
| JACKSON | 21 | 4% |
| LARAMIE | 18 | 4% |
| ROCK SPG | 17 | 3% |
| SHERIDAN | 17 | 3% |
| CODY | 15 | 3% |
| 84 other rate centers | 288 | 58% |
Who holds the prefixes in 307
Qwest holds the most prefixes, 83 (17%). 56% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Qwest | 83 | 17% |
| Union Telephone Company | 65 | 13% |
| Verizon Wireless | 60 | 12% |
| New Cingular Wireless PCS | 49 | 10% |
| Onvoy | 40 | 8% |
| Level 3 Communications | 27 | 5% |
| 46 other carriers | 173 | 35% |
A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company. Find which carrier a number is on, or browse the prefix holders.
History of area code 307
- 1947-01-01 Area code 307 went into service.
Area codes nearest to 307
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
ZIP codes in area code 307
86 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Cheyenne, WY | 8 |
| Casper, WY | 5 |
| Laramie, WY | 4 |
A ZIP code and an area code are unrelated systems. A ZIP code can sit in more than one area code, and an area code spans many ZIP codes.
Complaints on file for 307 numbers
2,968 FCC complaints are on file for 2,086 numbers in 307, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 80 |
| 2024 | 95 |
| 2025 | 86 |
Wyoming has one area code
307 is the only area code the table assigns to Wyoming, so every geographic number there starts with it.
Next to 307 in the numbering table
These are the codes just before and after 307 when all are sorted by number. They are neighbours on the list, not necessarily on the map.
What the area code does and does not tell you
A number that starts with 307 was first assigned in Wyoming. That is a fact about where the number began, and it is a useful hint when you check a form entry, for example a billing address in Wyoming next to a 307 phone number.
It does not show where the person is today. A number stays with its owner after a move or a change of provider (number portability), and mobile numbers travel with the handset. The area code also cannot tell you whether the line is active, who the carrier is, or whether the number is mobile or fixed: the plan shares those ranges. Read more about the area code, the numbering plan and line type.
Check numbers in bulk with the API
| Product | Credits | Docs |
|---|---|---|
| Phone Numbering-Plan Validation | 1 credit per valid number | API docs |
| Phone Intelligence (carrier and line status) | 1 credit per check (invalid numbers outside the US and Canada are free) | Product page |
Questions about area code 307
Where is area code 307?
NANPA assigns area code 307 to Wyoming, United States.
In which state does area code 307 sit?
Wyoming. 307 is one of 1 area code the NANPA table assigns to the state.
Which places does area code 307 cover?
The places with the most ZIP codes among the rate centers in 307 are Cheyenne, WY, Casper, WY and Laramie, WY. The rate center list on this page shows all of them.
Who owns area code 307?
NANPA assigns area codes. Within 307, Qwest holds the most prefixes, 83 prefixes or 17%.
Which time zone does 307 use?
The NANPA NPA report lists the time zone for 307 as Mountain (M).
What year did 307 enter service?
The NANPA NPA report gives an in-service date of 1947-01-01, so 307 has been in use since 1947.
Does area code 307 have an overlay?
The NANPA NPA report lists no other area code in an overlay with 307.
Which area codes are nearest to 307?
The area codes closest to 307, measured between the centers of the ZIP code places they serve, are 970 (about 227 miles), 303 (about 235 miles), 720 (about 235 miles), 983 (about 235 miles) and 385 (about 283 miles).
How many prefixes does area code 307 have?
NANPA's report dated 2026-10-17 lists 497 prefixes in service in 307, spread over 92 rate centers and 52 holders.
Are there complaints about 307 numbers?
The FCC data on file has 2,968 complaints for 2,086 numbers in 307. They are unverified consumer reports. A number with no complaints on file is not proven safe.
Area code assignments: North American Numbering Plan Administrator NPA report, file dated 10/17/2026, retrieved 2026-10-17. Source file. New codes are assigned several times a year. Prefixes, rate centers, holders, time zone, in-service date and overlays: NANPA central office code report dated 2026-10-17 and NPA report dated 2026-10-18. Complaints: FCC consumer complaints open data, fetched 2026-10-17. ZIP code places: Postal code places and coordinates: GeoNames (geonames.org), licensed CC BY 4.0.