Almost all of the Data communication systems across the world evolved from Telegraph systems. Later with developments in the telephone systems, it was now possible to interconnect various computer terminals for data communication. With the advancements in the network computing and the digitization of telephone networks, it was now possible to setup an efficient data communication network within each country and connecting such network with the world wide network.
For example in some countries, commercial data transmission was started with leased telephone live offered by DOT. DOT later supported PSTN (public switched telephone network) which is basically a dial up service. The speed of leased line and dial up services has been improved very much to coup up with changing needs and advancements in network computing. The leased line services are expensive and cannot support multiple speeds and protocols interworking. The dial up services on the other hand has the problem of long setup time, lower speed and problems specific to a country’s demography and inherent telephone network. Through decades, DOT makes improvements to leased line data services by introduction of line conditioning equipment, local digital data network and premium data services. DOT also supports modems on rent with test numbers to improve the PSTN dial up services.
Now for efficient and speedy data communication, DOT has launched many packet switched data networks (PSDN) that provides data communication services to about 20 locations in various parts of India. Such PSDNs can support speeds upto 64kbps for inter-city communications. RABMN or remote area business message network have been introduced which when connected to PSDN via a gateway provides data communication facilities between any location. Such a data communication network is a standard means of providing internet services.
With the development in the mobile communication and radio communications and integration of ISDN and other advanced FIOS networking, high speed data communication is possible that cab deliver high quality video, graphics and audio over high speeds.