The most expensive method of accessing the Internet is to employ leased lines that directly connect to the ISP. This will enhance access rate to anywhere between 64 K and 1.5 Mbps, based on the system in use. Equipment called data service units (DSU) & channel service units (CSU) are set up in pairs, one pair at the customer site & the other at the ISP site. There is no phone dialing needed since the connection is direct. Also the only protocol required to complete the access is TCP/IP, for much the similar reason. Based on the transfer rate needed and the distance between the sites, cabling amongst them can be made with fiber optic cables or unshielded twisted-pair (UTP) copper wire.