Everything about Telephony totally explained
In
telecommunication,
telephony (
or teh-LEH-fuh-nee) encompasses the general use of equipment to provide voice communication over distances, specifically by connecting
telephones to each other.
Telephones originally were connected directly together in pairs. Each user had separate telephones wired to the various places he might wish to reach. This became inconvenient when people wanted to talk to many other telephones, so the
telephone exchange was invented. Each telephone could then be connected to other local ones, thus inventing the
local loop and the
telephone call. Soon, nearby exchanges were connected together by
trunk lines, and eventually far away ones were.
In modern times, most telephones are plugged into
telephone jacks. Each jack is connected by
inside wiring to a
drop wire and then to a cable with other wires. Cables usually bring a large number of wires from all over a district
access network to one wire center or telephone exchange. When the user of a telephone wants to make a
telephone call, equipment at the exchange examines the dialed
telephone number and connects that
telephone line to another in the same wire center, or to a trunk to a distant exchange. Most of the exchanges in the world are connected to each other, forming the
Public Switched Telephone Network or PSTN. By the end of the 20th century almost all were
Stored Program Control exchanges.
Digital telephony is the use of digital technology in the provision of telephone services and systems. Almost all telephone calls are provided this way, but sometimes the term is restricted to cases in which the
last mile is digital, or where the conversion between digital and analog signals takes place inside the telephone. Telephony was digitized to cut the cost and improve the quality of voice services, but digital telephony was then found useful for new network services (
ISDN) to transfer data speedily over telephone lines.
IP Telephony is a modern form of telephony which uses the
TCP/IP protocol popularized by the
internet to transmit digitized voice data. Contrast this with the operation of POTS (an acronym for "
Plain Old Telephone Service").
Computer Telephony Integration (CTI) enables computers to know about and control phone functions such as making and receiving voice, fax, and data calls with telephone directory services and caller identification. The integration of telephone software and computer systems is a major development in the evolution of the automated office.
CTI isn't a new concept. Such links have been used in the past in large telephone networks but only dedicated call centers could justify the costs of the required equipment installation. Primary telephone service providers are offering information services such as
Automatic Number Identification and
Dialed Number Identification Service on a scale wide enough for its implementation to bring real value to business or residential telephone usage. A new generation of applications (middleware) is being developed as a result of standardization and availability of low cost computer telephony links.
Further Information
Get more info on 'Telephony'.
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