Area Code Atlas

Geographic Split of 423 (Tennessee) Numbering Plan Area (NPA); addition of 865 NPA

Permissive dialing period begins for 865 and 423

Permissive dialing began on October 1, 1999, allowing calls to Knoxville and the affected counties to be completed using either area code 423 or 865 during the transition period.

NPA 865 split from 423

Area code 865 was introduced for Knoxville and nine surrounding counties in East Tennessee on October 1, 1999, as a geographic split from area code 423. The split was implemented to address number exhaustion in the region, with 865 chosen to represent 'VOL' for the Tennessee Volunteers.

NPA 865 split from 423

On November 1, 1999, area code 865 was created for Knoxville and most of central East Tennessee, splitting from area code 423. The new code was chosen to correspond to 'VOL' for the University of Tennessee Volunteers. The split was implemented due to rapid number exhaustion in the region.

Permissive dialing period for 423 and 865

Permissive dialing of area code 423 continued across East Tennessee until April 22, 2000, allowing callers to use either 423 or the new 865 code during the transition period.

Mandatory dialing of area code 865

Mandatory dialing of area code 865 took effect on February 1, 2000, ending the permissive period and requiring all calls to Knoxville and the surrounding counties to use the new area code.

Mandatory dialing begins in area code 865

Mandatory dialing of area code 865 began on April 24, 2000, ending the permissive dialing period that followed the split from 423. This change required callers to dial the full ten-digit number to complete calls within the area.

Transition of area code 865 to ten-digit dialing

Area code 865 transitioned to mandatory ten-digit dialing on October 24, 2021, due to the nationwide designation of 988 as a three-digit code for the National Suicide Prevention Lifeline. This change was required to resolve conflicts with existing seven-digit dialing in exchanges using 988 as a central office code.