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