The 636 area code covers Saint Charles, Chesterfield and 36 more places in Missouri.
Area code 636 is in Missouri, on Central Time. In the 636 area, phone numbers are given out most in Saint Charles County, then St. Louis and Franklin counties. It has been in service since May 22, 1999.
- Where
- 7 counties in Missouri, mostly Saint Charles County, St. Louis County and Franklin County
- Time zone
- Central Time
- In service since
- May 22, 1999
- Shares its area with
- No other area code
- Prefixes in use
- 435
- How to dial
- Local calls inside 636 can still be dialed with just 7 digits.
Find out who called you from a 636 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (636) number is on today, use our free carrier lookup.
Works for US & Canada numbers. Enter a 10-digit number, e.g. (415) 555-0132.
Free & rate-limited. No signup required to try.
Saint Charles holds 10% of the phone prefixes in area code 636.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 435 prefixes in use shows where 636 numbers are actually given out.
- Saint Charles44 prefixes, 10%
- Chesterfield36 prefixes, 8%
- Harvester36 prefixes, 8%
- Manchester27 prefixes, 6%
- O Fallon24 prefixes, 6%
- Fenton16 prefixes, 4%
- Saint Peters15 prefixes, 3%
- Valley Park14 prefixes, 3%
Also served: Wentzville, Washington, Union and High Ridge and 26 smaller places.
Southwestern Bell (AT&T) holds the most phone number prefixes in area code 636: 110 of 435.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 435 prefixes in use in 636 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| Southwestern Bell (AT&T)AT&T's landline company | 110 | 25% |
| BrightspeedLandline company | 49 | 11% |
| T-MobileMobile network | 35 | 8% |
| AT&T MobilityMobile network | 29 | 7% |
| Level 3 (Lumen)Lumen's business and wholesale network | 29 | 7% |
| PAETEC (Windstream)Windstream's business phone network | 25 | 6% |
| 23 other carriers | 158 | 36% |
84% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
636 has covered the same ground since 1999.
1999
636 starts on May 22, 1999, split off from 314.
A 636 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 636 are 314, 573 and 618.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
These are the questions people ask most about area code 636.
Where is area code 636?
636 covers Saint Charles, Chesterfield, Harvester and Manchester and 34 more places in Missouri. In the 636 area, phone numbers are given out most in Saint Charles County, then St. Louis and Franklin counties.
What state is area code 636 in?
Missouri. 636 is a Missouri area code on Central Time.
What cities use area code 636?
The places holding the most 636 prefixes are Saint Charles, Chesterfield, Harvester, Manchester, O Fallon, Fenton, Saint Peters and Valley Park, out of 38 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 636?
No single phone company owns 636. NANPA's records show Southwestern Bell (AT&T) holds the most 636 prefixes, 110 of 435, followed by Brightspeed and T-Mobile. Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 636 in?
636 is on Central Time.
When did area code 636 start?
636 went into service on May 22, 1999, when it was split off from 314.
How do I dial a 636 number?
Local calls inside 636 can still be dialed with just 7 digits.
Is 636 a toll-free number?
No. 636 is a regular area code for Saint Charles and Chesterfield in Missouri, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 636?
The closest are 314/557 (Saint Louis, Missouri), 573/235 (Columbia, Missouri), 618/730 (Collinsville, Illinois) and 217/447 (Springfield, Illinois), measured between the centres of each area.
Who called me from a 636 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 636 a scam?
636 is a real Missouri area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.