Most IBM computer systems are connected together using coaxial cables with BNC connectors. These cables are fairly expensive to buy and costly to install. On the other hand, most buildings are already wired for telephone systems and it is quite easy to take advantage of this existing wiring to connect computer equipment.
With a pair of Patton Electronics Model 400 units, any IBM 3270 Type A equipment can be connected together over one twisted pair telephone line at distances up to 1200 feet (365m)! This can result in significant savings!