The 301 area code covers Washington, D.C. suburbs, Frederick and 41 more places in Maryland.
Area code 301 is in Maryland, on Eastern Time. In the 301 area, phone numbers are given out most in Frederick County, then Montgomery and Charles counties. It has been in service since 1947. 227 and 240 cover the same area, so two neighbours can have different area codes.
- Where
- 8 counties in Maryland, mostly Frederick County, Montgomery County and Charles County
- Time zone
- Eastern Time
- In service since
- 1947, one of the original area codes
- Shares its area with
- 227 (since 2023) and 240 (since 1997)
- Prefixes in use
- 784
- How to dial
- Local calls need all 10 digits: 301-555-0142.
Find out who called you from a 301 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 (301) number is on today, use our free carrier lookup.
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Washington, D.C. suburbs holds 63% of the phone prefixes in area code 301.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 784 prefixes in use shows where 301 numbers are actually given out.
- Washington, D.C. suburbs495 prefixes, 63%
- Frederick37 prefixes, 5%
- Gaithersburg33 prefixes, 4%
- Laurel28 prefixes, 4%
- Waldorf25 prefixes, 3%
- Hagerstown21 prefixes, 3%
- Cumberland14 prefixes, 2%
- Ashton11 prefixes, 1%
Also served: Damascus, Leonardtown, Myersville and Oakland and 31 smaller places.
Of the carriers named here, AT&T Mobility holds the most phone number prefixes in area code 301: 47 of 784.
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 784 prefixes in use in 301 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| AT&T MobilityMobile network | 47 | 6% |
| Teleport (AT&T)AT&T's business phone network | 33 | 4% |
| T-MobileMobile network | 31 | 4% |
| Level 3 (Lumen)Lumen's business and wholesale network | 20 | 3% |
| Metro by T-MobileT-Mobile's prepaid brand | 14 | 2% |
| Comcast (Xfinity)Cable company's phone service | 12 | 2% |
| 21 other carriers | 627 | 80% |
51% 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.
301 has been split once and overlaid 2 times since 1947.
1947
301 is one of the original North American area codes.
1991
On October 6, 1991, 410 splits off and takes part of the 301 area.
1997
On June 1, 1997, 240 is added on top of 301, so new numbers here can get either code.
2023
On June 14, 2023, 227 is added on top of 301, so new numbers here can get either code.
A 301 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 301 are 703, 202 and 717.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
Maryland has 5 other area codes.
These are the questions people ask most about area code 301.
Where is area code 301?
301 covers Washington, D.C. suburbs, Frederick, Gaithersburg and Laurel and 39 more places in Maryland. In the 301 area, phone numbers are given out most in Frederick County, then Montgomery and Charles counties.
What state is area code 301 in?
Maryland. 301 is a Maryland area code on Eastern Time.
What cities use area code 301?
The places holding the most 301 prefixes are Washington, D.C. suburbs, Frederick, Gaithersburg, Laurel, Waldorf, Hagerstown, Cumberland and Ashton, out of 43 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 301?
No single phone company owns 301. NANPA's records list its 784 prefixes across many carriers, and the ones named on this page include AT&T Mobility, Teleport (AT&T) and T-Mobile. Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 301 in?
301 is on Eastern Time.
When did area code 301 start?
301 is one of the original North American area codes, in service since 1947.
Is 301 the same area as 227 and 240?
Yes. 227 (since 2023) and 240 (since 1997) cover the same ground as 301. Nobody's number changed when they were added; new lines simply get whichever code has numbers left, so two neighbours can have different codes.
How do I dial a 301 number?
Local calls need all 10 digits: 301-555-0142.
Is 301 a toll-free number?
No. 301 is a regular area code for Washington, D.C. suburbs and Frederick in Maryland, 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 301?
The closest are 703/571 (Washington, D.C. suburbs, Virginia), 202/771 (Washington, D.C.), 717/223 (Harrisburg, Pennsylvania) and 410/443/667 (Baltimore, Maryland), measured between the centres of each area.
Who called me from a 301 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 301 a scam?
301 is a real Maryland 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.