Discount Computer Parts Center's Telephone Line Video Balun provides you with a cost-efficient and convenient way to transmit video signals up to 660ft. With this unit, you can use your existing telephone cable installed in your home or place of business to connect your video surveillance devices. This professional grade unit is great for video surveillance. Normal in-wall telephone cables contain 6 individual wires. While a single telephone number requires only 1 pair of wires, 2 pairs (or 4 wires) are left unused.