another network, IVAO, which was more European-oriented, unlike SATCO, which was more American-oriented. The board drew up terms of agreement with Randy Whistler, the then President of SATCO, declaring VATSIM the official successor of SATCO. In 2020, VATSIM announced it had achieved 100,000 active users for the first time, an increase of 20,000 users in two years. SquawkBox and ProController The advent of the Internet in the mid-1990s enabled users of modern flight simulators to fly together using multiplayer functionality. In 1997, SquawkBox was created by Jason Grooms as an add-on for Microsoft Flight Simulator 95, enhancing the built-in multiplayer features to allow large numbers of players to connect to the game. ProController, a radar-simulation program also developed by Jason Grooms, was created in the same year to connect virtual pilots with virtual controllers. The FSD Server was created by Marty Bochane to provide the signaling infrastructure and logic required to integrate ProController and Squawkbox, enabling users to fly in real-world weather conditions. ProController was retired as an approved ATC client on March 13, 2004. ASRC and Roger Wilco Sometime in 2002, ProController was slowly being phased out in favour of ASRC (Advanced Simulated Radar Client), created by Mike Evans and David Hendleman, and was released to the public in early 2003. Alongside that, Roger Wilco (software) was used to facilitate voice communications between pilots and ATC, with ATC denoting that voice communications were available with them with the callsign format XXXX_V_TWR, alongside putting their voice server IP and voice room name in their ATIS. Later, however, Roger Wilco was phased out in favour of the Advanced Voice Client, which required VATSIM authentication to prevent any non-VATSIM users from logging into the voice servers. The ASRC software was retired as an ATC client on April 1, 2021, due to its not being in active development, which will make it incompatible with fast position updates that will be brought with VATSIM Velocity. On March 27, 2005, an alternative add-on to FS2002/FS2004 and FSX called FSInn was approved for use on the VATSIM network alongside SquawkBox. VRC and EuroScope On April 17, 2006, the VRC ATC client was approved for use on the VATSIM network. Created by Ross Carlson, as of May 2020, the VRC client is still in use today - mainly in the American and Oceanic regions, due to its easy setup, but comes with a lack of customisability. On