Area codes 678 and 470
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Area codes 678 and 470 are telephone area codes of the North American Numbering Plan (NANP) in the U.S. State of Georgia for metropolitan Atlanta. Both area codes are assigned in an overlay plan to a combined numbering plan area (NPA) consisting of 404 (Atlanta and its suburbs inside Interstate 285) and 770 (Atlanta suburbs and exurbs outside 285).
Telephone numbers in area code 678 were first assigned to customers signing up for new telephone service on January 15, 1998, while 470 was activated on February 26, 2010.  Although ten-digit dialing was used in the Atlanta area since area code 770 was introduced in 1995, it was not until January 1, 1998, when 678 was implemented, that ten-digit dialing finally became required across the entire metro area. 
All central office prefixes of numbering plan area 404 are assigned to service providers, the last having been issued in October 2013.  Prefixes 678 and 770 have also all been allocated, leaving only 470 central office codes available, although previously-used numbers are always available for reassignment to new customers. Despite existing for decades before this change, the largest customer using area code 470 is Kennesaw State University in Kennesaw, which was forced to change hundreds of telephone numbers when the Georgia Board of Regents forced schools in the University System of Georgia to implement internal telephone systems, and the FCC failed to make local number portability applicable to businesses and government,[ citation needed] allowing AT&T to refuse KSU to take its numbers to the new provider. Kennesaw State University opted to use 470-578 (KSU) as their number prefix for the new phone numbers, outside of the normal geographical calling area for Kennesaw; 470-578 numbers are based in Atlanta Northeast  and Kennesaw State University is located in the Atlanta Northwest calling area. 
The entire metro Atlanta region with area code 404, 770, and 678/470, is a local calling area, one of the largest in the United States. No long-distance charges are applied for calls from one portion of the area to another, regardless of the area codes; calls can complete with just ten digits. Portions of area codes 706 and 762, which serve most of north Georgia outside the Atlanta metro, are local calls to and from the Atlanta area as well.
Area codes 678 and 470 serve the counties of Barrow, Bartow, Butts, Carroll, Cherokee, Clayton, Cobb, Coweta, DeKalb, Douglas, Fayette, Forsyth, Fulton, Gwinnett, Hall, Haralson, Heard (part with area codes 706 and 762), Henry, Lamar, Meriwether (part with area codes 706 and 762), Newton, Oconee, Paulding, Pike, Polk, Rockdale, Spalding, and Walton.
- "NANP Administration System". Nanpa.com. 2010-02-26. Archived from the original on 2012-02-24. Retrieved 2012-09-29.
- "North America Numbering Plan Planning Letter" (PDF). Nanpa.com. Retrieved 2012-09-29.
- "No more 404, 678 area codes given in Atlanta". M.ajc.com. Retrieved 11 July 2018.
- Chow, Ray. "Local calling guide: NPA-NXX search". Localcallingguide.com. Retrieved 2017-01-20.
- Chow, Ray. "Local calling guide: Rate centre information". Localcallingguide.com. Retrieved 2017-01-20.
|West: 256/ 938||678/470 (overlaying 404 and 770)||East: 706/ 762|
|South: 478, 706/762|
|Alabama area codes: 205/659, 251, 256/938, 334|