50 Pair Telephone Cable is ideal for voice applications and is commonly used for telephone purposes. It has fewer twists than Cat5e, which makes it easier to work with when punching it down. It also has no spinal divider, like the Cat6 cable does. Cat3 plenum is mandatory to use where a plenum fire rating is required. It has a Teflon jacket rather than polyvinyl chloride (PVC) and gives off less toxic fumes in a fire.