Lucent Technologies 5 manual About TelecommunicationsB, Telephone Extension Equipment

MERLIN LEGEND Communications System Release 5.0	Issue 1
System Manager’s Guide 555-650-118	June 1997
B About Telecommunications
Telephone Extension Equipment	Page B-1
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About TelecommunicationsB

Many of the terms and concepts involved in telephone communications have been in use since Alexander Graham Bell made the first phone call in 1876. Because understanding them will help you to understand how the system works, this section contains a brief history and description of telephone communications.

Basically, telephone communications involves four elements:

■Telephone Extension Equipment (also referred to by an older term, telephone station equipment). The telephone instrument and/or other equipment (for example, a fax machine) used to transmit and receive the telephone signal.

■Transmission Facilities. The equipment and media (for example, wire, cable, and optical fiber) that provide the communications path that carries the telephone signal.

■Switching Equipment. The equipment that makes the electrical cross connections so that the caller is connected to the called party.

■Signaling. The transmission of information that controls the network, for example, alerting the switch that a user wants to make a call, transmitting the telephone number of the called party, and alerting the called party of the call. Signals also tell the switch about how to make the connections.

This appendix provides information about each of the elements.

Telephone Extension Equipment 2

Telephone extension equipment is the user’s gateway to the global communications network and an array of services. While today’s telephones range from single-line telephones to multiline telephones with various features and options, telephone extension equipment can now also involve such things as