It's a reference to the University of Tennessee Volunteers. The station, formerly WKXT NewsChannel 8, relaunched in the late 90's as "WVLT, Volunteer TV." Long #3 in the local ratings, the station made an effort to increase their sports presence, expanding the sportscast to take up the last 10 minutes of each newscast.
Slowly but surely, it worked and the station is now a solid #2 in the market. This past fall, WVLT won the contract with Host Communications/IMG to be the flagship station of the Vol Network, carrying coaches shows for the three major sports at UT (Football, Men's and Women's bball) as well as "Inside the Orange," which focuses on baseball, softball and other spring sports, and they also show UT Football rebroadcasts produced by the Vol Network on their subchannel, MyVLT2.