With the prospect of 423 being exhausted by 1999, it soon became apparent that East Tennessee needed another area code, even though this would have forced some residents to change their numbers for the second time in a decade.
The Tennessee Regulatory Authority requested that the code 865 be assigned to Knoxville when the area was split from 423.
This was because on a standard telephone keypad, the numbers 865 correspond to the letters VOL, the commonly used short version of Volunteers, which is the formal nickname of the sports teams at the University of Tennessee.
Overlays were a new concept at the time, and met with some resistance due to the need for ten-digit dialing.
865 began its split on October 1, 1999; permissive dialing of 423 continued throughout East Tennessee until February 1, 2000.