Railway Minister Suresh Prabhu on Friday launched free Wi-Fi service at three more railway stations across India via videoconferencing here.These stations are at Patna in Bihar, Visakhapatnam in Odisha and Ranchi in Jharkhand. So far, Mumbai Central, Bhubaneshwar, Kachiguda, Vijayawada, Raipur, Bhopal and Jaipur have got Wi-Fi facility.The minister said the government planned to introduce the service at all major railway stations in the country in three years."By this year-end, free Wi-Fi facility will be in place at 100 major railway stations. We will achieve our target of 400 stations in three years. Once in place, it will be the largest public Wi-Fi system in the world," Prabhu told reporters here.The service was commissioned by RailTel, a mini-Ratna public sector undertaking, in association with Google for providing high-speed internet to rail commuters at these places.The services will be provided under 'Railwire', the retail broadband distribution model of Railtel.Mumbai Central was the first railway station in the country with free Wi-Fi facility.Last year, Google India and Indian Railways joined hands to introduce high-speed Wi-Fi network at 400 stations in the country.