---
title: "Area code 636: Missouri, United States"
url: "https://lookvalid.com/area-code/636.md"
canonical_url: "https://lookvalid.com/area-code/636"
last_updated: "2026-10-23"
type: "reference"
summary: "Area code 636 serves Missouri, United States. Number formats, numbering rules, a live phone validator and the other codes in Missouri."
---

# Area code 636: Missouri, United States

Area code 636 serves Missouri, United States. Number formats, numbering rules, a live phone validator and the other codes in Missouri.

NANPA lists 430 central office codes (prefixes) in use in area code 636, held by 30 holders across 46 rate centers.
Southwestern Bell holds the most prefixes, 110 (26%). 84% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
The FCC unwanted-call data has 1,701 complaints on file for 1,380 numbers in 636, most often filed as "Unwanted Calls". These are consumer reports, not findings.

## Facts

- 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

| 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% |

## Carriers

| 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.

## History

- 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.

## Nearest area codes

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).

## ZIP codes

36 ZIP codes fall in places that have a rate center in this area code. The places with the most are Saint Charles, MO (4 ZIP codes), Fenton, MO (2 ZIP codes) and O Fallon, MO (2 ZIP codes). A ZIP code and an area code are unrelated systems, so a ZIP code can sit in more than one area code and an area code spans many ZIP codes.

## Complaints on file

1,701 complaints for 1,380 numbers. Numbers whose latest complaint falls in each year:

- 2023: 84
- 2024: 121
- 2025: 270

## Questions

### 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.

Sources: NANPA central office code report dated 2026-10-17; NANPA NPA report dated 2026-10-18; FCC unwanted-call complaints, data fetched 2026-10-17; ZIP code places from GeoNames (CC BY 4.0).