Area code
636
636 is a United States area code. Under the North American Numbering Plan it belongs to Missouri, which has 9 area codes in total.
Validate a number in 636
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 636 at a glance
NANPA lists 430 central office codes (prefixes) in use in area code 636, held by 30 holders across 46 rate centers.
| Fact | Value |
|---|---|
| In service since | 1999-05-22 |
| Time zone | Central (C) |
| Prefixes in use | 430 |
| Pooled prefixes | 363 (84%) |
| Rate centers | 46 |
| Companies holding prefixes | 30 |
| Assignment dates on file | 2001-01-18 to 2026-04-02 (177 prefixes) |
| ZIP codes in its places | 36 |
Rate centers in area code 636
| Rate center | Prefixes | Share |
|---|---|---|
| ST CHARLES | 43 | 10% |
| CHESTERFLD | 35 | 8% |
| HARVESTER | 35 | 8% |
| MANCHESTER | 27 | 6% |
| OFALLON | 23 | 5% |
| FENTON | 16 | 4% |
| FSSCRSTLCY | 16 | 4% |
| ST PETERS | 15 | 3% |
| 38 other rate centers | 220 | 51% |
Who holds the prefixes in 636
Southwestern Bell holds the most prefixes, 110 (26%). 84% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Southwestern Bell | 110 | 26% |
| Brightspeed Of Missouri | 49 | 11% |
| T-Mobile USA | 35 | 8% |
| Onvoy | 33 | 8% |
| Level 3 Communications | 29 | 7% |
| New Cingular Wireless PCS | 29 | 7% |
| 24 other carriers | 145 | 34% |
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 636
- 1947-01-01 Area code 314, named as the parent of 636 in the NANPA report, was in service.
- 1999-05-22 Area code 636 went into service.
Area codes nearest to 636
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
- 314 about 27 mi
- 557 about 27 mi
- 573 about 50 mi
- 235 about 60 mi
- 618 about 92 mi
ZIP codes in area code 636
36 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Saint Charles, MO | 4 |
| Fenton, MO | 2 |
| O Fallon, MO | 2 |
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 636 numbers
1,701 FCC complaints are on file for 1,380 numbers in 636, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 84 |
| 2024 | 121 |
| 2025 | 270 |
Other area codes in Missouri
Missouri is one state with 9 area codes in the NANPA table. 636 is one of them.
Next to 636 in the numbering table
These are the codes just before and after 636 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 636 was first assigned in Missouri. 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 Missouri next to a 636 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 636
Where is area code 636?
NANPA assigns area code 636 to Missouri, United States.
In which state does area code 636 sit?
Missouri. 636 is one of 9 area codes the NANPA table assigns to the state.
Which places does area code 636 cover?
The places with the most ZIP codes among the rate centers in 636 are Saint Charles, MO, Fenton, MO and O Fallon, MO. The rate center list on this page shows all of them.
Who owns area code 636?
NANPA assigns area codes. Within 636, Southwestern Bell holds the most prefixes, 110 prefixes or 26%.
Which time zone does 636 use?
The NANPA NPA report lists the time zone for 636 as Central (C).
What year did 636 enter service?
The NANPA NPA report gives an in-service date of 1999-05-22, so 636 has been in use since 1999.
Does area code 636 have an overlay?
The NANPA NPA report lists no other area code in an overlay with 636.
Which area codes are nearest to 636?
The area codes closest to 636, measured between the centers of the ZIP code places they serve, are 314 (about 27 miles), 557 (about 27 miles), 573 (about 50 miles), 235 (about 60 miles) and 618 (about 92 miles).
How many prefixes does area code 636 have?
NANPA's report dated 2026-10-17 lists 430 prefixes in service in 636, spread over 46 rate centers and 30 holders.
Are there complaints about 636 numbers?
The FCC data on file has 1,701 complaints for 1,380 numbers in 636. 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.