U.S. Air Force Airman 1st Class Chad Humphries, 39th Communications Squadron cyber transport technician, tests the voice and networking signals on a 66 punch down block using a tone tester set. The 66 block connects the end users to the telephone systems' main distribution hub on base, while the tone tester checks for connectivity or inconsistencies in the connection. (U.S. Air Force photo by Staff Sgt. Jason Huddleston)