<P> From 1947 to 1990, it was possible for telephone users in the northern Virginia portion of 703 to dial any number in the Washington metropolitan area with only seven digits . While the Washington metro area is split between three area codes--Maryland's 301, the District's 202, and 703--it was a single local calling area . Every number in the Maryland and Virginia portions of the metro area was protected from assignment in the District's 202, essentially making 202 an overlay for the entire metro . One consequence of this was that no central office prefix could be duplicated anywhere in the Washington metro area . For instance, if a 1 - 202 - 574 number was in use in the District or a 1 - 301 - 574 was in use on the Maryland side of the metro, the corresponding 1 - 703 - 574 number could only be used in areas considered a safe distance from the Washington metro area, such as Roanoke and the Tri-Cities . By the end of the 1980s, the D.C. area was running out of numbers, so the partial overlay of 202 was ended in 1990 . </P> <P> However, it soon became apparent that breaking seven - digit dialing in the Washington area would not free up enough numbers to keep up with demand on either side of the Potomac River . With this in mind, on June 19, 1995, most of the western portion of the old 703 area code was split off into the new area code 540, and 703 was restricted to northern Virginia . The same issue had forced the split of area code 410 from 301 four years earlier . </P> <P> The 1995 split was intended to be a long - term solution . However, within four years, 703 was close to exhaustion due to the proliferation of cell phones, fax machines, and pagers, as well as northern Virginia's explosive growth . To solve this problem, area code 571 was introduced on March 1, 2000, as an overlay to 703 . Area code 571 serves most new telephone numbers; while it is primarily associated with mobile telephone lines, it is also used for new landline numbers, including the United States Patent and Trademark Office upon moving to Alexandria; the Transportation Security Administration, which was created in 2001 and has its headquarters in Arlington; and the Fairfax County Public Schools, which moved its headquarters to the Falls Church area in 2006 . </P> <P> Although former competitors Bell Atlantic (a former Baby Bell) and GTE had assigned geographical monopolies varying by region in Virginia, they merged in the late 1990s to form Verizon, now the dominant local telephone service provider throughout Virginia, including both of these area codes . Over 85% of all telephone numbers in both of these area codes are served by Verizon, a regulated monopoly . </P>

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