Eventually, it prepared the continent for direct-dialing of long-distance calls by customers, first possible in 1951 and expanded across the nation during the decades following.

AT&T continued to administer the continental numbering plan and the technical infrastructure until the end of the Bell System, when administration was delegated to the North American Numbering Plan Administrator (NANPA), a service that has been procured from the private sector by the Federal Communications Commission (FCC) in the United States.

These systems expanded by growing their subscriber bases, as well as enlarging their service areas by implementing additional local exchanges that were interconnected with tie trunks.

[5] As a result, the North American telephone service industry developed into an unorganized set of many differing local numbering systems.

The diversity impeded the efficient operation and interconnection of exchanges into a nationwide system for long-distance telephone communication.

Although Bermuda and the Caribbean islands had been assigned the area code 809 as early as 1958 by the administrators at AT&T, individual participating countries or territories had no autonomy over their numbering plan as they received centrally assigned central office prefixes that needed to be unique from those of other countries with the same area code.

[citation needed] During the decades following, the NANP expanded to include all of the United States and its territories, Canada, Bermuda, and seventeen nations of the Caribbean.

Before the breakup of the Bell System, administration of the North American Numbering Plan was performed by AT&T's Central Services Organization.

Local numbering plans, many of which required only four or five digits to be dialed, or even fewer in small communities, needed to be expanded.

NPAs were created in accordance with principles deemed to maximize customer understanding and minimize dialing effort, while reducing plant cost.

An important aspect was the existing infrastructure for call routing, which had developed during preceding decades, often independently of state boundaries.

Six states (Indiana, Kansas, Massachusetts, Minnesota, Missouri, Wisconsin) and two provinces (Ontario, Quebec) were divided into two NPAs.

Traditionally, central office switching systems were designed to serve as many as ten thousand subscriber numbers.

The digit 0 was used for operator assistance, and 1, which is essentially a single pulse of loop interruption, was automatically ignored by most switching equipment of the time.

Finally, they sought the elimination of central office names and letter codes, and introduced all-number calling (ANC).

NANP telephone numbers are formally rendered as NPA-NXX-XXXX, but (NPA) NXX-XXXX is common, as are others forms of punctuation.

The North American Numbering Plan does not reserve special non-geographic area codes exclusively for cellular phones, as is customary in some other national telephone administrations.

The widespread adoption of fax, modem, and mobile phone communication, as well as the deregulation of local telecommunication services in the United States during the mid-1990s, increased the demand for telephone numbers.

Atlanta was the first U.S. city to require mandatory ten-digit dialing throughout the metropolitan area, coinciding roughly with the 1996 Summer Olympics held there.

Also, many splits involved significant technical issues, considering municipal boundaries and tributary trunking arrangements.

Before 1995, all NANP countries and territories outside the contiguous United States, Alaska, Hawaii and Canada shared the area code 809.

[14] The NANP exhaust analysis estimates that the existing numbering system is sufficient beyond 2049, based on the assumptions that a maximum of 674 NPAs continue to be available, and that on average 3,990 central office codes are needed per year.

Other proposals include reallocating blocks of numbers assigned to smaller long-distance carriers or unused reserved services.

The 112 code is gaining prevalence because of its preprogrammed presence in mobile telephones that conform to the European GSM standard.

[54] The FCC regulations were enacted on June 27, 1996, with changes to take effect in the one hundred largest Metropolitan Statistical Areas by October 1, 1997, and elsewhere by December 31, 1998.

[citation needed] Because of these higher fees, scams had taken advantage of customers' unfamiliarity with pricing to call the legacy regional area code 809.

Similarly, the movie BUtterfield 8 is set in the East Side of Manhattan between roughly 64th and 86th Streets, where the telephone prefixes include 288.

Despite the phasing out of the letter system, alphabetic phonewords remain as a commercial mnemonic gimmick, particularly for toll-free numbers.

Where used, these are often routed to information services; Canadian telephone companies briefly promoted 555-1313 as a pay-per-use "name that number" reverse lookup during the mid-1990s.

The 1962 Motown hit "Beechwood 4-5789" was written by Marvin Gaye for The Marvelettes, while Stax/Volt Records' Wilson Pickett scored a soul music success during the 1960s with the similarly named "634-5789".