is done inside the terminals, and riders pay the additional fare upon entering these buses. Connecting inter-city transit agencies Via Rail and Amtrak connect with the TTC at Union Station, while Ontario Northland, Megabus, TOK Coachlines and US-bound Greyhound intercity coaches connect with the TTC at the Union Station, Scarborough Centre, , and Yorkdale bus terminals. Cellular and Wi-Fi connectivity The communication system used by surface vehicles is called the Communications and Information System. It was piloted in the 1970s, implemented in 1991, and is now deployed on all TTC surface vehicles. Wi-Fi service is provided at all TTC subway stations through the TCONNECT Wi-Fi network provided by BAI Communications. The service is supported by advertising and is free for users. , the Wi-Fi network was installed at all existing stations and will be available in all future stations. From early December 2015 to late January 2016, commuters had to sign on to Twitter, through a sponsorship deal with the social media network, in order to use the subway stations' Wi-Fi network. This arrangement was resumed on an optional basis from July 2016 to late November/early December 2016. On June 17, 2015, the TTC announced that Wind Mobile (later rebranded Freedom Mobile) customers could access cellular connectivity at some TTC subway stations. BAI Communications has built a shared Wi-Fi and cellular infrastructure for the TTC that allows any wireless carrier to sign on and provide underground cellular service to their customers. As of December 2017, BAI's cellular DAS is operational at all 75 TTC stations. Freedom Mobile users also have Wi-Fi and cellular coverage in the tunnels on Line 1 between Vaughan Metropolitan Centre and Sheppard West stations and between Bloor–Yonge and St. George stations. Accessibility The Wheel-Trans door-to-door service has been available since the mid-1970s. Since the 1990s, the TTC has focused on providing accessible services on conventional bus routes, the RT and subway. 56 of the 75 stations on Lines 1, 2, and 3 are wheel-chair accessible are equipped with elevators, and all stations on Line 4 are fully accessible. In December 2011, all bus routes became accessible with the retirement of the commission's last inaccessible buses. On August 31, 2014, the commission launched its new fleet of low-floor Bombardier's Flexity Outlook streetcars. With the decommissioning of the last of the Commission's non-accessible high-floor CLRV vehicles on December 29, 2019, all TTC streetcar routes are now served by