You can create a direct link to another computer by running RS-232 cables between serial ports on the two machines. Direct links are useful when two computers communicate regularly and are physically close, such as within 50 feet of each other. You can use a limited-distance modem to increase this distance somewhat.
By using an automatic call unit (ACU), such as a high-speed modem, your machine can communicate with other computers over standard phone lines. The modem dials the telephone number that is requested by UUCP. The recipient machine must have a modem that is capable of answering incoming calls.
UUCP can also communicate over a network that runs TCP/IP or another protocol family. After your computer has been established as a host on a network, your computer can contact any other host that is connected to the network.
This chapter assumes that your UUCP hardware has already been assembled and configured. If you need to set up a modem, refer to System Administration Guide: Basic Administration and the manuals that accompanied the modem for assistance.