--- title: "Area code 301: Maryland, United States" url: "https://lookvalid.com/area-code/301.md" canonical_url: "https://lookvalid.com/area-code/301" last_updated: "2026-10-23" type: "reference" summary: "Area code 301 serves Maryland, United States. Number formats, numbering rules, a live phone validator and the other codes in Maryland." --- # Area code 301: Maryland, United States Area code 301 serves Maryland, United States. Number formats, numbering rules, a live phone validator and the other codes in Maryland. NANPA lists 784 central office codes (prefixes) in use in area code 301, held by 29 holders across 64 rate centers. Verizon Maryland holds the most prefixes, 463 (59%). 51% of the prefixes are pooled, which means their thousands-blocks can belong to different companies. The FCC unwanted-call data has 5,767 complaints on file for 4,355 numbers in 301, most often filed as "Unwanted Calls". These are consumer reports, not findings. ## Facts - 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 | 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% | ## Carriers | 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. ## History - 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. ## Nearest area codes 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). ## ZIP codes 84 ZIP codes fall in places that have a rate center in this area code. The places with the most are Baltimore, MD (42 ZIP codes), Frederick, MD (6 ZIP codes) and Hagerstown, MD (6 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 5,767 complaints for 4,355 numbers. Numbers whose latest complaint falls in each year: - 2023: 200 - 2024: 236 - 2025: 174 ## Questions ### 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. 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).