When the
American Telephone and Telegraph Company (AT&T) divided the North American continent into the original eighty-six numbering plan areas (NPAs) for the first nationwide
telephone numbering plan in 1947, Wisconsin received two area codes,
414 for the south and northeast, and
715, for the northern part.
On November 22, 1996, Ameritech notified
Bellcore, the
North American Numbering Plan Administration (NANPA), that demand for telephone numbers had rapidly increased in the eastern part of the state, so that a jeopardy condition existed in which mitigation could not provided early enough to avoid exhaustion of the numbering pool.[1]
On January 15, 1997, the NANP announce a split of the numbering plan area to create the new area code 920,[2] in which Milwaukee and the surrounding communities south of the city would retain the existing area code, and the northern portion of the numbering plan area would receive 920. The split became effective on July 26, 1997, and a permissive dialing period ended on October 25, 1997.[3]
In 2008, service providers recognized the need for a second area code for northeastern Wisconsin, leading the
Public Service Commission of Wisconsin to approve an
overlay plan with new area code 274.[4][5] The effective date for the new area code was announced as March 10, 2012. However, on December 22, 2010, PSC ordered a postponement of the plan due to new exhaustion forecasts for 2014.[6] The
Great Recession, number porting, a decline in
landlines, and other factors delayed that requirement for fifteen years during which implementation was deferred several times.[7][8]
Prior to October 2021, area code 920 had telephone numbers assigned for the
central office code 988. In 2020, 988 was designated nationwide as a dialing code for the
National Suicide Prevention Lifeline, which created a conflict because area code 920 permitted
seven-digit dialing. 920 transitioned to
ten-digit dialing on October 24, 2021.[9]
On December 8, 2008, the Public Service Commission finally approved an all-services distributed overlay as the relief method for NPA 920 and on March 16, 2022, the NANPA established the time line for installation, setting the in-service date of area code 274 to March 22, 2024. Only months later, based on new exhaust studies,[10] this timeline was revised to May 5, 2023.[11]