Consider the scope of the operation. Indian Railways is the world's second-largest railway, with 6,853 stations, 63,028 kilometers of track, 37,840 passenger coaches and 222,147 freight cars. Annually it carries some 4.83 billion passengers and 492 million tons of freight.

Of the 11 million passengers who climb aboard one of 8,520 trains each day, about 550,000 have reserved accommodations. Their journeys can start in any part of India and end in any other part, with travel times as long as 48 hours and distances up to several thousand kilometers. The challenge is to provide a reservation system that can support such a huge scale of operations - regardless of whether it's measured by kilometers, passenger numbers, routing complexity, or simply the sheer scale of India.

PRS started in 1985 as a pilot project in New Delhi. The avowed objective was to provide reserved accommodation on any train from any counter preparation of train charts and accountal of the money collected. When initial pilot project was implemented at Delhi, the software (referred to as version I) had a number of limitations. These were mainly removed in next version i.e. version II implemented in in 1987.With the addition of new locations and many redefinitions needed the new version III evolved in 1990.Even the version III of the earlier software called Impress fell far short of the growing expectations of he travelling public and the need was felt to have a software which has the capabilities of providing the Networking of the five independent PRS nodes namely Secundrabad, Delhi, Calcutta, Mumbai and Chennai

On 18^th April 1999, with the networking of Chennai PRS, all the five PRS namely Secunderabad, New Delhi, Kolkata, Mumbai and Chennai were finally networked together.

Now anywhere to anywhere reserved ticketing became a possibility on any PRS booking terminal. In order to facilitate the availability, PNR status and other journey planning information to the common public various interfaces like the Interactive Voice Response System (IVRS) on the telephone, Touch Screens at selective locations, RAPID, DISPLAY, Passenger Operated Enquiry Terminals (POET) and Daily Press Availability Reports through newspapers have been provided.