Area codes 301 and 240

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Area codes 215, 267, and 445Area code 856Area code 484Area code 717Area code 814Area code 724Area code 202Area code 571Area codes 757 and 948Area code 302Area codes 410, 443, and 667Area code 304/681Area code 804Area code 434Area code 540area codes 240 and 301 possibly 308. These numbers are related to the main zip codes of Maryland.
Maryland consists of the red and blue areas. The red area indicates area codes 240 and 301. This map is clickable; click on any neighboring area code to go to the page for that code.

Area codes 301 and 240 are telephone area codes in the North American Numbering Plan (NANP) for the western part of the U.S. state of Maryland. The numbering plan area (NPA) comprises Maryland's portion of the Greater Washington, D.C. metro area, portions of southern Maryland, along with rural western Maryland. This includes the communities of Cumberland, Frederick, Hagerstown, Gaithersburg, Potomac, Germantown, Bethesda, Rockville, Landover, Silver Spring, and Waldorf.

History

Establishment

Area code 301 was one of the original area codes when the NANP was established in 1947. It served the entire state of Maryland.

Much of the Washington metropolitan area is part of a local calling area which is centered on the District's area code 202, and also extends into the suburban area in southern Maryland with 301 and Northern Virginia with area code 703. From 1947 to 1990, it was possible to dial any other telephone number in the metro area as a local call with only seven digits, not using an area code, irrespective of the home area code. The entire metro area was also reachable via long-distance services by dialing area code 202, for which purpose AT&T had established cross-referenced operator routing codes for all affected central offices.[1] For example, if 202-574 numbers were in use in the District or 703-574 numbers were in use in Northern Virginia, the corresponding 301-574 numbering block could only be assigned in areas considered a safe distance away from the capital, such as the Eastern Shore of Maryland.

Ten-digit dialing

By the end of the 1980s, the Washington metropolitan area was running out of unassigned prefixes for new central offices. The only available prefixes could not be assigned without breaking seven-digit dialing in the region. With this in mind, the three local operating companies of The Chesapeake and Potomac Telephone Company (C&P Telephone, later part of Bell Atlantic and now Verizon) decided to mitigate this situation by ending the code protection scheme as of October 1, 1990, with the result that all local metro area calls between Maryland, the District of Columbia, and Virginia required dialing the area code for calls to another NPA.[2] Area code 202 was no longer useable for suburban points. Local calls within Maryland did not require the area code.[3] Permissive dialing using the old dialing procedures continued from April 1 through October 1 1990.[4]

Split

Despite the overall growth of the Baltimore–Washington metropolitan area, 301 remained the exclusive area code for Maryland for 44 years, making Maryland one of the largest states with a single area code. By the end of the 1980s, however, it became apparent that breaking seven-digit dialing in the Washington area would not free up enough numbers north of the Potomac River to stave off the immediate need for a new area code.

Baltimore and the Eastern Shore were split off as area code 410 on November 1, 1991.[5][6] The split largely followed metropolitan area lines. There were a few exceptions, such as in Howard County, which is often recognized as part of the Baltimore metropolitan area, a small portion of the county remained in area 301, while the rest of the county was reassigned to area code 410.[7]

Normally, when an area code is split, the largest city in the old numbering plan area retains the existing area code—in this case, Baltimore. In this case, however, Bell Atlantic wanted to spare the large number of federal agencies on the Maryland side of metropolitan Washington from the expense and disruption of changing their numbers.

First overlay

This was intended as a long-term solution, but within four years 301 was close to exhaustion due to the proliferation of cell phones and pagers, especially in the Washington suburbs. In order to solve this problem, area code 240 was introduced on June 1, 1997, as the state's first overlay area code.[8] Overlays were a new concept at the time, and met with some resistance due to the requirement for ten-digit dialing.[9] It was decided to create an overlay rather than split the region into two new regions in order to avoid assigning a new area code to 1.2 million existing phone numbers.[10] At the time, it was predicted that it would take until 2008 to exhaust area code 240.[11]

Second overlay

In September 2022, it was projected that the 301 and 240 area codes would be exhausted between April and June 2023.[12] The North American Numbering Plan Administrator has assigned area code 227 as an additional overlay for the region.[13] Phone numbers with area code 227 only begin to be assigned on June 14, 2023. However, existing phone numbers with area codes 301 and 240 will not change, even after 227 enters service. [14][13] Existing phone numbers will not change.[13]

Service area

The counties served by area codes 301 and 240 include all of Allegany, Charles, Garrett, Montgomery, Prince George's, St. Mary's and Washington counties, most of Frederick County,[a] western Howard County,[a], and slivers of southwestern Carroll County[a] and western Anne Arundel County.[a]

Local calls require ten-digit dialing (area code + number, leading "1" is not required).

Notes

  1. ^ a b c d Four counties were split between area code 301 and 410.
    • In Anne Arundel County, Laurel exchanges 210, 317, 490, 497, 498, 596, 604, 725, and 778 and Marlboro exchange 952 remained area code 301. The rest of the county was assigned ara code 410.
    • In Carroll County Mount Airy exchange 829 remained area code 301. The rest of the county was assigned area code 410.
    • In Howard County, Mount Airy exchange 829 and Laurel exchanges 210, 317, 490, 497, 598, 604, 725, and 776 remained area code 301. The rest of the county was assigned area code 410.
    • Most of Frederick County remained area code 301. Only Union Bridge exchange 775 and New Windsor exchange 635 were assigned area code 410.[15]

References

  1. ^ AT&T Long Lines, Distance Dialing Reference Guide (April 1974) This was implemented via a system of central office code protection, meaning that no central office code in the metro area could exist in more than a single central office.
  2. ^ "Area Codes Needed to Call Between Md., D.C., Va." The Baltimore Sun. October 1, 1990. p. 2B.
  3. ^ Jordan, Mary; Quimpo, Margie G. (September 23, 1990). "Territorial Telephones; On Oct. 1, Local Calls Will Get Complicated". The Washington Post. p. 1.
  4. ^ NANPA Bellcore Information Letter IL-90/04-003
  5. ^ Muth, Charlie (November 17, 1990). "Shore to Get New Area Code". The Daily Times (Salisbury, Maryland). p. 1, 4.
  6. ^ Hetrich, Ross (October 25, 1991). "New Area Code 410 Starts Nov. 1 in Half of State". The Baltimore Evening Sun. p. C12.
  7. ^ "Bellcore Letter IL-90/12-049" (PDF). North American Numbering Plan Administration. Neustar. Retrieved June 21, 2013.
  8. ^ "Bellcore Letter IL 96/06-009" (PDF). North American Numbering Plan Administration. Neustar. Retrieved 21 June 2013.
  9. ^ Yates, Jennifer C. (April 22, 1997). "Maryland Gets Read for 10-digit Dialing". Associated Press. The Star-Democrat (Easton, Maryland). p. A1.
  10. ^ "Ready for 10-digit Stroll?". The Daily Times (Salisbury, Maryland). January 23, 1997. p. 4.
  11. ^ Pemberton, Mary (May 2, 1997). "10-digit Dialing Comes to Maryland". Associated Press. The Gettysburg Times (Gettysburg, Pennsylvania). p. A3.
  12. ^ "2022-1 NRUF and NPA Exhaust Analysis" (PDF). North American Numbering Plan Administrator. April 21, 2021. Retrieved July 15, 2021.
  13. ^ a b c Duffy, Ken (September 28, 2022). "New Area Code Coming to Parts of Maryland". WBAL.
  14. ^ "Area Code Changes".
  15. ^ "New area code for eastern Maryland". The Baltimore Sun. November 1, 1991. p. 1A.

External links

Maryland area codes: 240/301, 410/443/667
North: 223/717, 412/724/878, 814
West: 202, 304/681, 540, 571/703 area codes 240/301 East: 410/443/667
South: 804, 304/681
District of Columbia area codes: 202
Pennsylvania area codes: 215/267/445, 223/717, 272/570, 412, 484/610, 724, 814/582, 878
Virginia area codes: 276, 434, 540, 571/703, 757/948, 804
West Virginia area codes: 304/681
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