Area code 917 is a telephone area code for all five boroughs of New York City (Brooklyn, Manhattan, Queens, Staten Island, and the Bronx). It was the first cellular/pager/voicemail area code for the city and is an overlay to Manhattan's 212/646 and the other four boroughs' 718/347/929. Occasionally, 917 is also assigned to landlines, most commonly in Manhattan, in large part because of the particularly severe shortage of numbers there.
Introduced in 1992, area code 917 is the first overlay area code in the North American Numbering Plan. When it was established, all cellphones in New York City were switched to 917, freeing up telephone numbers for additional landlines.
Shortly after its implementation, the FCC announced that any new area codes going forth must not be service-specific, but did grandfather 917 from that rule. It is the last area code added under the original X1X format, whose last digit was not 0.