Area codes 410, 443, and 667

Area codes 410, 443 and 667 are telephone area codes serving the eastern half of the U.S. state of Maryland, including the Baltimore metropolitan area and the Eastern Shore. The 410 area code is the main area code, while the 443 and 667 codes are overlay codes. 443 and 667 were primarily used with cell phones and CLEC carriers such as Comcast or Cavalier Telephone when introduced but have since become universal in their carrier availability.

Before these area codes were created, all of Maryland had been served by 301 since the institution of area codes in 1947. However, by the end of the 1980s, the rapid growth of the Baltimore and Washington, D.C. suburbs made it apparent that a second area code was necessary. The supply of available numbers was further limited by the fact that most of the Maryland side of the Washington area shares an LATA with Northern Virginia and the District itself. In 1991, state officials came up with a plan to add a second area code, the 410 code, to the state. They eventually decided that the Baltimore metropolitan area and the Eastern Shore would get the new area code, while the western and southern parts of Maryland—including the Washington suburbs—would remain with the 301 area code.

410 officially entered service on October 6, 1991; it is not known whether it was implemented as a flash-cut or permissive dialing was allowed for a time. Within only five years of its creation, 410 was already close to exhaustion due to the area's rapid growth and the proliferation of cell phones and pagers. To solve this problem, 443 was overlaid onto the 410 territory on July 1, 1997. Overlays were a new concept at the time, and had met with some resistance due to the prospect of different area codes in the same area as well as the requirement for ten-digit dialing. However, Verizon, the dominant carrier in the region, wanted to keep residents from having to change their numbers.

By 2011, the 410/443 area was running out of numbers, again due to the proliferation of cell phones. Again, to prevent residents from having to change their phone numbers to a new area code, the overlay of 667 was implemented on March 24, 2012.^[1]

The counties served by these area codes include:

In the Baltimore metropolitan area:

On the Eastern Shore:

References

^ Fazeli Fard, Maggie (12 October 2011). "Maryland's new 667 area code goes into effect in 2012". The Washington Post. Retrieved 23 July 2012.

External links

"Area Code Maps". NANPA.

Maryland area codes: 301/240/227, 410/443/667
	North: 717, 484/610/835
West: 301/240	area codes 410/443/667	East: 302, Atlantic Ocean
	South: 757
Delaware area codes: 302
Pennsylvania area codes: 215/267/445, 412, 570/272, 610/484/835, 717/223, 724, 814/582, 878
Virginia area codes: 276, 434, 540/826, 703/571, 757/948, 804/686

[1] Fazeli Fard, Maggie (12 October 2011). "Maryland's new 667 area code goes into effect in 2012". The Washington Post. Retrieved 23 July 2012.

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