Atlanta's five area codes
470 and 943 cover the entire combined footprint of 404, 770, and 678; there's no way to tell which of the five an Atlanta number carries just by knowing what part of the metro its owner lives in. Assignment depends only on when the line was activated. Miami's numbering history starts the same year as Atlanta's: one of its area codes, 305, also dates to 1947 and once covered the entire state of Florida before growth split the rest of the state away from it, the same kind of single-code-to-many split Atlanta went through starting decades later.
Atlanta's area codes and whether each still issues new numbers
| Area code | Coverage | In service since | Still issuing new numbers? |
|---|---|---|---|
| 404 | Georgia (statewide in 1947; Atlanta inside the I-285 perimeter today) | 1947 (original) | No (exhausted October 2013) |
| 770 | Metro Atlanta outside the I-285 perimeter | August 1, 1995 | No (exhausted) |
| 678 | Overlay on 404 and 770 | January 6, 1998 | No (exhausted) |
| 470 | Overlay on 404, 770, and 678 | February 26, 2010 | Yes |
| 943 | Overlay on 404, 770, 678, and 470 | March 15, 2022 | Yes |
Three splits carved Georgia down to just metro Atlanta
404 was one of the original 86 area codes the North American Numbering Plan assigned in 1947, and it started out covering the entire state of Georgia, not just Atlanta. Three splits over the next 48 years narrowed it down to roughly its present footprint. The first, on July 1, 1954, cut off the southern half of the state as area code 912, leaving 404 running from the Tennessee and North Carolina lines south to Columbus and Augusta.
That boundary held for 38 years. On May 3, 1992, regulators split off nearly everything outside the immediate Atlanta area as area code 706, shrinking 404 to roughly the metro region. The third and final geographic split came just three years later: on August 1, 1995, 404 was divided along the Interstate 285 perimeter highway, with everything outside it becoming area code 770. That 1995 line is the last one Georgia's numbering plan has ever drawn. Every area code assigned to metro Atlanta since has been an overlay across an existing footprint, not a new geographic boundary.
Three overlays in 24 years, each covering more ground than the last
678 went into service January 6, 1998, as an overlay spanning both 404 and 770 at once, the first time a single new Atlanta code crossed the 1995 perimeter line instead of respecting it. That set the pattern every later addition followed. 470 arrived February 26, 2010, overlaying all three existing codes (404, 678, and 770); NANPA's senior director at the time described it publicly as intended primarily for downtown Atlanta and the surrounding area, though like every other overlay it was assignable anywhere in the combined footprint.
By October 2020, exhaustion analyses were projecting that the four-code combination would run out of assignable prefixes by the second quarter of 2023. The Georgia Public Service Commission approved a fifth code that month, and NANPA assigned 943; it went into service March 15, 2022, overlaying 404, 770, 678, and 470 simultaneously. The new code's footprint reaches well beyond Atlanta's city limits: it covers the same PSC-defined region as the four codes before it, including Alpharetta, Duluth, Dunwoody, East Point, Forest Park, Gainesville, Griffin, Lawrenceville, Mableton, Marietta, Peachtree City, Roswell, Sandy Springs, Smyrna, and Tucker. The same shift from geographic splits to stacked overlays, once a region runs out of room to redraw lines, shaped Chicago's numbering plan and New York City's outer-borough codes.
404, 678, and 770 still work; they just can't be assigned to anyone new
"Exhausted" describes the supply of unassigned central office prefixes within a code, not the code itself. Every 404, 678, and 770 number already in service keeps working exactly as before; nothing about exhaustion forces a number to change. What exhaustion means in practice is that phone carriers can no longer request new blocks of numbers from any of the three codes. When a carrier needs numbers for new customers in the Atlanta overlay region, NANPA assigns them from 470 or 943 instead, the only two codes that still have prefixes left to give out.
404's exhaustion is documented precisely: every central office prefix in the code had been assigned to a service provider by October 2013. 678 and 770 exhausted later: both were fully allocated by the time regulators approved 943 in October 2020, the same shortfall projected to hit the whole four-code combination by the second quarter of 2023. 470 was added in 2010, well ahead of any of that, because overlay codes are typically requested years before a projected exhaustion date rather than after it arrives.