Area code
301
301 is a United States area code. Under the North American Numbering Plan it belongs to Maryland, which has 6 area codes in total.
Validate a number in 301
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 301 at a glance
NANPA lists 784 central office codes (prefixes) in use in area code 301, held by 29 holders across 64 rate centers.
| Fact | Value |
|---|---|
| In service since | 1947-01-01 |
| Time zone | Eastern (E) |
| Assigned overlays | 240 (1997-06-01), 227 (2023-06-14) |
| Prefixes in use | 784 |
| Pooled prefixes | 397 (51%) |
| Rate centers | 64 |
| Companies holding prefixes | 29 |
| Assignment dates on file | 2002-01-09 to 2025-07-01 (62 prefixes) |
| ZIP codes in its places | 84 |
Rate centers in area code 301
| Rate center | Prefixes | Share |
|---|---|---|
| WSHNGTNZN3 | 112 | 14% |
| WSHNGTNZN2 | 88 | 11% |
| WSNG236Z13 | 53 | 7% |
| WSNGTNZN10 | 52 | 7% |
| WSHNGTNZN4 | 47 | 6% |
| FREDERICK | 37 | 5% |
| WSHNGTNZN5 | 37 | 5% |
| GAITHERSBG | 33 | 4% |
| 56 other rate centers | 325 | 41% |
Who holds the prefixes in 301
Verizon Maryland holds the most prefixes, 463 (59%). 51% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Verizon Maryland | 463 | 59% |
| Verizon Wireless | 51 | 7% |
| New Cingular Wireless PCS | 47 | 6% |
| Mcimetro Access Transmission Services | 43 | 5% |
| Teleport Communications America | 33 | 4% |
| Omnipoint Communications Cap Operations | 31 | 4% |
| 23 other carriers | 116 | 15% |
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 301
- 1947-01-01 Area code 301 went into service.
- 1991-10-06 Area code 410 went into service and names 301 as its parent.
- 1997-06-01 Area code 240 went into service as an overlay in the same area as 301.
- 2023-06-14 Area code 227 went into service as an overlay in the same area as 301.
Area codes nearest to 301
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
Overlay codes in the same area
ZIP codes in area code 301
84 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Baltimore, MD | 42 |
| Frederick, MD | 6 |
| Hagerstown, MD | 6 |
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 301 numbers
5,767 FCC complaints are on file for 4,355 numbers in 301, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 200 |
| 2024 | 236 |
| 2025 | 174 |
Other area codes in Maryland
Maryland is one state with 6 area codes in the NANPA table. 301 is one of them.
Next to 301 in the numbering table
These are the codes just before and after 301 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 301 was first assigned in Maryland. 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 Maryland next to a 301 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 301
Where is area code 301?
NANPA assigns area code 301 to Maryland, United States.
In which state does area code 301 sit?
Maryland. 301 is one of 6 area codes the NANPA table assigns to the state.
Which places does area code 301 cover?
The places with the most ZIP codes among the rate centers in 301 are Baltimore, MD, Frederick, MD and Hagerstown, MD. The rate center list on this page shows all of them.
Who owns area code 301?
NANPA assigns area codes. Within 301, Verizon Maryland holds the most prefixes, 463 prefixes or 59%.
Which time zone does 301 use?
The NANPA NPA report lists the time zone for 301 as Eastern (E).
What year did 301 enter service?
The NANPA NPA report gives an in-service date of 1947-01-01, so 301 has been in use since 1947.
Does area code 301 have an overlay?
Yes. 240 (in service 1997-06-01) and 227 (in service 2023-06-14) share the same area with 301, so numbers from all of them are local to each other.
Which area codes are nearest to 301?
The area codes closest to 301, measured between the centers of the ZIP code places they serve, are 571 (about 33 miles), 703 (about 33 miles), 443 (about 44 miles), 410 (about 47 miles) and 667 (about 47 miles).
How many prefixes does area code 301 have?
NANPA's report dated 2026-10-17 lists 784 prefixes in service in 301, spread over 64 rate centers and 29 holders.
Are there complaints about 301 numbers?
The FCC data on file has 5,767 complaints for 4,355 numbers in 301. 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.