Telephony
Encyclopedia
In telecommunication
s, telephony (icon ) encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other.. The technology is associated with the electronic transmission of voice, fax, or other information between distant parties using systems historically associated with the telephone
, a handheld device containing both a speaker or transmitter and a receiver. It is commonly referred to as the construction or operation of telephones or telephonic systems and as a system of telecommunications in which telephonic equipment is employed in the transmission of speech or other sound between points, with or without the use of wires. .
To break the term down into further detail, telephony is the science of translating sound into electrical signals, transmitting them, and then converting them back to sound; that is, the science of telephones. The term is used frequently to refer to computer hardware and software that performs functions traditionally performed by telephone equipment. For example, telephony software can combine with your modem to turn your computer into a sophisticated answering service. A popular example of this type of telephony software is voice mail .
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 by trunk lines
, and eventually distant ones were as well.
In modern times, most telephones are plugged into telephone jack
s. The jacks are connected by inside wiring
to a drop
wire which connects the building to a cable. Cables usually bring a large number of drop 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
(PSTN). By the end of the 20th century almost all were stored program control exchange
s.
After the middle of the 20th century, fax and data became important secondary users of the network created to carry voices, and late in the century, parts of the network were upgraded with ISDN and DSL to improve handling of such traffic.
Today, telephony has been digitized and has merged into digital telephony
, the use of digital technology in the provision of telephone services and systems. Telephone calls can be provided digitally, but are restricted to cases in which the last mile
is digital, or where the conversion between digital and analog signals takes place inside the telephone. This advancement has reduced costs in communiciation and improved the quality of voice services. This has been found useful for new network services (ISDN
) that transfer data speedily over telephone lines.
Another important concept that has been merged into telephony is computer telephony integration
, which 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. The term is used in describing the computerized services of call centers, such as those that direct your phone call to the right department at a business you're calling. It's also sometimes used to describe the ability to use your personal computer to initiate and manage phone calls (in which case you can think of your computer as your personal call center). CTI is not a new concept and has 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
, which is is a telephone service architecture that separates CTI services from call switching and will make it easier to add new services. Dialed Number Identification Service
(DNIS) on a scale is 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.
") technically called the PSTN (public-switched telephone network).
This system is being fiercely challenged by and to a great extent yielding to Voice over IP (VoIP) technology, which is also commonly referred to as IP Telephony and Internet Telephony. IP telephony is a modern form of telephony which uses the TCP/IP protocol popularized by the Internet
to transmit digitized voice data. Also, unlike traditional phone service, IP telephony service is relatively unregulated by government. In the United States, the Federal Communications Commission (FCC) regulates phone-to-phone connections, but says they do not plan to regulate connections between a phone user and an IP telephony service provider.Using the Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The challenge in IP telephony is to deliver the voice, fax, or video packets in a dependable flow to the user. Much of IP telephony focuses on that challenge..
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s, telephony (icon ) encompasses the general use of equipment to provide communication over distances, specifically by connecting telephones to each other.. The technology is associated with the electronic transmission of voice, fax, or other information between distant parties using systems historically associated with the telephone
Telephone
The telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
, a handheld device containing both a speaker or transmitter and a receiver. It is commonly referred to as the construction or operation of telephones or telephonic systems and as a system of telecommunications in which telephonic equipment is employed in the transmission of speech or other sound between points, with or without the use of wires. .
To break the term down into further detail, telephony is the science of translating sound into electrical signals, transmitting them, and then converting them back to sound; that is, the science of telephones. The term is used frequently to refer to computer hardware and software that performs functions traditionally performed by telephone equipment. For example, telephony software can combine with your modem to turn your computer into a sophisticated answering service. A popular example of this type of telephony software is voice mail .
Brief Overview
Telephones were originally connected directly together in pairs. Each user would have a separate telephone wired to various places he might wish to reach. This became inconvenient when people wanted to communicate with many other people using telephones, so the telephone exchangeTelephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
was invented. Each telephone could then be connected to other local ones, thus inventing the local loop
Local loop
In telephony, the local loop is the physical link or circuit that connects from the demarcation point of the customer premises to the edge of the carrier or telecommunications service provider's network...
and the telephone call
Telephone call
A telephone call is a connection over a telephone network between the calling party and the called party.-Information transmission:A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile...
. Soon, nearby exchanges were connected by trunk lines
Trunking
In modern communications, trunking is a concept by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of...
, and eventually distant ones were as well.
In modern times, most telephones are plugged into telephone jack
Telephone plug
A telephone plug is a type of male connector used to connect a telephone to the telephone wiring in a home or business, and in turn to a local telephone network. It is inserted into its female counterpart, a telephone "jack", commonly affixed to a wall or baseboard...
s. The jacks are connected by inside wiring
On-premises wiring
In telecommunication, on-premises wiring is customer-owned communications transmission lines. It is also called customer premises wiring . The transmission lines can be metallic or optical fiber, and may be installed within or between buildings.Premises wiring may consist of horizontal wiring,...
to a drop
Drop (telecommunication)
Drop, in telecommunication, has several meanings.* In a communications network, a drop is the portion of a device directly connected to the internal station facilities, such as toward a telephone switchboard, toward a switching center, or toward a telephone exchange. A drop can also be a wire or...
wire which connects the building to a cable. Cables usually bring a large number of drop wires from all over a district access network
Access network
An access network is that part of a telecommunications network which connects subscribers to their immediate service provider. It is contrasted with the core network, which connects local providers to each other...
to one wire center or telephone exchange. When the user of a telephone wants to make a telephone call
Telephone call
A telephone call is a connection over a telephone network between the calling party and the called party.-Information transmission:A telephone call may carry ordinary voice transmission using a telephone, data transmission when the calling party and called party are using modems, or facsimile...
, equipment at the exchange examines the dialed telephone number
Telephone number
A telephone number or phone number is a sequence of digits used to call from one telephone line to another in a public switched telephone network. When telephone numbers were invented, they were short — as few as one, two or three digits — and were given orally to a switchboard operator...
and connects that telephone line
Telephone line
A telephone line or telephone circuit is a single-user circuit on a telephone communication system...
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
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
(PSTN). By the end of the 20th century almost all were stored program control exchange
Stored Program Control exchange
Stored Program Control exchange is the technical name used for telephone exchanges controlled by a computer program stored in the memory of the system. Early exchanges such as Strowger, panel, rotary, and crossbar switches were electromechanical and had no software control...
s.
After the middle of the 20th century, fax and data became important secondary users of the network created to carry voices, and late in the century, parts of the network were upgraded with ISDN and DSL to improve handling of such traffic.
Today, telephony has been digitized and has merged into digital telephony
Digital telephony
Digital telephony is the use of digital electronics in the provision of digital telephone services and systems. Since the 1960s a digital core network has almost entirely replaced the old analog system, and much of the access network has also been digitized...
, the use of digital technology in the provision of telephone services and systems. Telephone calls can be provided digitally, but are restricted to cases in which the last mile
Last mile
The "last mile" or "last kilometer" is the final leg of delivering connectivity from a communications provider to a customer. The phrase is therefore often used by the telecommunications and cable television industries. The actual distance of this leg may be considerably more than a mile,...
is digital, or where the conversion between digital and analog signals takes place inside the telephone. This advancement has reduced costs in communiciation and improved the quality of voice services. This has been found useful for new network services (ISDN
Integrated Services Digital Network
Integrated Services Digital Network is a set of communications standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network...
) that transfer data speedily over telephone lines.
Another important concept that has been merged into telephony is computer telephony integration
Computer telephony integration
Computer telephony integration, also called computer–telephone integration or CTI, is a common name for any technology that allows interactions on a telephone and a computer to be integrated or coordinated...
, which enables computers to know about and control phone functions such as making and receiving voice, fax, and data calls with telephone directory
Telephone directory
A telephone directory is a listing of telephone subscribers in a geographical area or subscribers to services provided by the organization that publishes the directory...
services and caller identification. The integration of telephone software and computer systems is a major development in the evolution of the automated office. The term is used in describing the computerized services of call centers, such as those that direct your phone call to the right department at a business you're calling. It's also sometimes used to describe the ability to use your personal computer to initiate and manage phone calls (in which case you can think of your computer as your personal call center). CTI is not a new concept and has 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
Automatic number identification
Automatic number identification is a feature of telephony intelligent network services that permits subscribers to display or capture the billing telephone number of a calling party. In the United States it is part of Inward Wide Area Telephone Service . ANI service was created by AT&T for...
, which is is a telephone service architecture that separates CTI services from call switching and will make it easier to add new services. Dialed Number Identification Service
Dialed Number Identification Service
Dialed Number Identification Service is a service sold by telecommunications companies to corporate clients that lets them determine which telephone number was dialed by a customer. This is useful in determining how to answer an inbound call. The Telecommunications company sends a DNIS number to...
(DNIS) on a scale is wide enough for its implementation to bring real value to business or residential telephone usage. A new generation of applications (middleware
Middleware
Middleware is computer software that connects software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact...
) is being developed as a result of standardization and availability of low cost computer telephony links.
Recent Developments
The term’s scope has been broadened with the advent of the different new communication technologies. In its broadest sense, the terms encompasses phone communication, Internet calling, mobile communication, faxing, voicemail and video conferencing. Telephony's initial idea returns to POTS, (an acronym for "plain old telephone servicePlain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
") technically called the PSTN (public-switched telephone network).
This system is being fiercely challenged by and to a great extent yielding to Voice over IP (VoIP) technology, which is also commonly referred to as IP Telephony and Internet Telephony. IP telephony is a modern form of telephony which uses the TCP/IP protocol popularized by the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
to transmit digitized voice data. Also, unlike traditional phone service, IP telephony service is relatively unregulated by government. In the United States, the Federal Communications Commission (FCC) regulates phone-to-phone connections, but says they do not plan to regulate connections between a phone user and an IP telephony service provider.Using the Internet, calls travel as packets of data on shared lines, avoiding the tolls of the PSTN. The challenge in IP telephony is to deliver the voice, fax, or video packets in a dependable flow to the user. Much of IP telephony focuses on that challenge..
See also
- Digital TelephonyDigital telephonyDigital telephony is the use of digital electronics in the provision of digital telephone services and systems. Since the 1960s a digital core network has almost entirely replaced the old analog system, and much of the access network has also been digitized...
- List of telephony terminology
- History of the telephone
- Invention of the telephoneInvention of the telephoneThe invention of the telephone is the culmination of work done by many individuals, the history of which involves a collection of claims and counterclaims. The development of the modern telephone involved an array of lawsuits founded upon the patent claims of several individuals...
- Push-button telephonePush-button telephoneThe push-button telephone was first invented in 1941, and is a telephone with push-buttons or keys, and which eventually replaced rotary dial telephones that were first used in 1891. The first push-button telephone was invented in the labs of Bell Telephone; however, these models were only...
- TelephoneTelephoneThe telephone , colloquially referred to as a phone, is a telecommunications device that transmits and receives sounds, usually the human voice. Telephones are a point-to-point communication system whose most basic function is to allow two people separated by large distances to talk to each other...
- VideotelephonyVideotelephonyVideotelephony comprises the technologies for the reception and transmission of audio-video signals by users at different locations, for communication between people in real-time....