Area Code Atlas

NPA 205 split to create 251

In 2001, area code 205 was split to form area code 251, serving Mobile and southwestern Alabama. This split created 251 as a new area code for southwestern Alabama, including Mobile, while 205 remained in the northern and central regions.

334 NPA Split, Creating 251 NPA (Alabama)

Area code 251 created as a split from 334

On June 18, 2001, area code 251 was created as a split from area code 334 to serve southwestern Alabama, including Mobile, Baldwin, and Washington counties. The split was implemented to accommodate the growing demand for telephone numbers in the region.

Permissive dialing period for 251 and 334

Permissive dialing for area code 251 began on June 18, 2001, allowing calls to be completed using either 334 or 251 in the affected region. This transition period continued until January 7, 2002, to give residents and businesses time to adjust to the new area code.

Mandatory Dialing of Area Code 251

On January 7, 2002, the permissive dialing period ended, making the use of area code 251 mandatory in the new region of Southwestern Alabama. Prior to this date, calls could be completed using either 334 or 251, allowing time for transition.

Transition to 10-digit dialing in 251 for 988 implementation

On October 24, 2021, area code 251 transitioned to mandatory 10-digit dialing to resolve conflicts with the new 988 code for the National Suicide Prevention Lifeline. This change was required for all regions permitting seven-digit dialing and affected all customers in the 251 area.