Telecommunication is an array of technologies involved in transmitting information over a distance. It used transmitters like smoke signals, semaphore, and drums in earlier times and today, it uses telephone, radio, television, computer, and networks for sending information. Some of the latest telecommunication technologies include mobile phones, land lines, satellite phones, and Voice over Internet Protocol (VoIP).

Components of Telecommunication System

  • Transmitter – The device that takes information and converts it into a signal is called the transmitter. Example: Broadcasting Tower
  • Transmission medium – The medium that is ideal to carry the signal is called the transmission medium. Example: Free Space
  • Receiver -The device that receives the signal and converts it back into usable information is called the receiver. Example: Radio
  • Transceiver -The device that acts as both a transmitter and receiver is called the transceiver. Example: Mobile phone
  • Point to Point – The transmission between a single transmitter and receiver is called the point-to-point communication.
  • Broadcast – The transmission between a single powerful transmitter and many receivers is called the broadcast communication.
  • Signal – The special data that is used to set up and control communication is called the signal. It can be either analogue or digital.
  • Analog – It varies with the information and degrades due to noise during transmission.
  • Digital – It has information encoded as a set of discrete values and remains intact during transmission.
  • Network – The complete setup including the transmitters, receivers or transceivers for telecommunication is called the network.
  • Analog Network – It has one or more switches to establish connection.
  • Digital Network – It has one or more routers to route information.
  • Channel – The medium that sends multiple streams of information is called the channel.
  • Modulation – The process of modifying the signal to convey information is called the modulation.


  • Early Times – The drums and smoke signals were used by the natives in America.
  • Middle Ages – The chains of beacons were used on hilltops to convey a single bit of information.
  • 1792 – Claude Chappe designed the visual telegraphy system (semaphore) between Lille and Paris.
  • 1837 – Samuel Morse developed the electrical telegraph.
  • 1839 – Sir Charles Wheatstone and Sir William Fothergill Cooke built the first commercial electrical telegraph.
  • 1866 – The first transatlantic telegraph cable was laid.
  • 1876 – Alexander Bell and Elisha Gray invented conventional telephone.
  • 1878-79 – The first commercial telephone services were started between New Haven and London.
  • 1832– James Lindsay introduced the concept of wireless telegraphy.
  • 1893 – Nikola Tesla demonstrated small scale radio communication.
  • 1901 – Guglielmo Marconi setup a wireless communication between Newfoundland (Canada) and Cornwall (England).
  • 1925 – John Logie Baird invented mechanical television.
  • 1929 – British Broadcasting Corporation (BBC) was established.
  • 1940 – The configuration of a centralized computer or mainframe with remote dumb terminals started.
  • 1960 – Packet switching was implemented using different computers.
  • 1969 – ARPANET was established and the Request for Comment (RFC 1) was published.
  • 1981 – RFC 791 introduced the Internet Protocol v4 (IPv4) and Transmission Control Protocol (TCP) laying basis for internet transmission.
  • 1989 – Neptune pictures taken from the Voyager 2 spacecraft was transmitted to earth laying basis for satellite communication.

Telecommunication Vs Internet

Traditionally, telecommunications and on-line computer services are different, operated on different platforms and regulated by different regulators. But the convergence of these two different media into one operating platform has enabled new convergent services like internet through TV, web casts, voice telephony etc. It has led to new technology called the Computer telephony integration (CTI) that integrates or co-ordinates interactions between a telephone and a computer. It integrates all of the customer contact channels with computer systems.

There are two forms of CTI. They are :

  • First-party call control – It operates like a direct connection between the computer and phone. All functions of the phone are controlled by the computer.
  • Third-party call control – It operates on a dedicated telephony server that acts as an interface between the telephone network and computer network. The user computer has no direct connection to phone and it sends commands to telephony server which in turn controls the phone.
  • Some of the functions of CTI are as follows.
  • Retrieve call related information such as caller’s number (ANI), number dialed (DNIS), and screen population on answer.
  • Blend multi-channel requests of phone, e-mail, and web.
  • Automatic computer controlled dialing
  • Phone control operations like log on, answer, hang up, hold, conference, etc.
  • Data transfer between parties
  • Call routing and reporting

The CTI application event flow has the following sequence.

CTI flow chart

The CSTA standard approved by the ITU is adopted by most vendors. Other CTI standards include JTAPI (Sun), TSAPI (AT&T) and TAPI (Microsoft).

The CTI applications are built around the Computer-supported telecommunications applications (CSTA) which became an OSI standard in 2000. Its core has a Call Control model with call associated and physical device features. The three major revisions of CSTA are Phase 1, Phase 2, and Phase 3. The protocols used by CSTA are SIP, H323, and ACSE/ROSE.

Telecommunication Vs Mobile

The convergence of telecommunication and mobile phones has led to many new technologies. One such technology is the Universal Mobile Telecommunications System (UMTS) that uses W-CDMA as the underlying air interface. Also referred to as 3GSM, UMTS combines the 3G nature of the technology with GSM standard. When compared to GSM, UMTS has the air interface that forms Generic Radio Access Network (GeRAN). This allows connection to various backbone networks like the Internet, ISDN, and GSM network.

UMTS networks in many countries are now in the process of upgrading to High Speed Downlink Packet Access (HSDPA) with downlink transfer speeds of up to 7.2 Mbit/s. Also, the work on upgrading to High-Speed Uplink Packet Access (HSUPA) with uplink transfer speeds of up to 5.76 Mbit/s is progressing. By using a next generation air interface technology based upon OFDM, 3GPP Long Term Evolution project plans to move UMTS to 4G speeds of 100 Mbit/s down and 50 Mbit/s up are also initiated.