communications in which messages are transmitted along wires by means of electrical signals; a type of telecommunication. The messages may be voice transmissions received by listening (telephone communications), or they may be transmitted and received by means of equipment that records and reproduces the messages in the form of arbitrary symbols or letters and numbers (telegraph communications and data transmission). Messages may also be in the form of fixed images, such as photographs, drawings, and illustrations (facsimile communications), moving images (television), or the image and speech of subscribers (videotelephone). A distinction is made between long-distance (intercity) and local (intracity) wired communications.
Wired communications make use of underground communications cables (less often, overhead lines), electronic signal amplifiers (repeaters) inserted into connecting cables at specified points, and terminal apparatus of various types, depending on the type of wired communications used. Various telecommunications systems combine wired communications with radio communication, such as radio-relay and satellite communications (seeSPACECRAFT COMMUNICATIONS).