OnStar Corporation is a subsidiary of General Motors that provides subscription-based communications, in-vehicle security, emergency services, turn-by-turn navigation, and remote diagnostics systems throughout the United States, Canada, China, Mexico, Europe, Brazil, Colombia, Argentina and the Gulf Cooperation Council countries.
A similar service known as "Vauxhall/Opel OnStar" was available in western Europe and "ChevyStar" in Latin American markets (except in Mexico, Brazil and Argentina). In September 2011 the president of OnStar stated that the service had more than six million customers. On May 9, 2018, Vauxhall Motors announced that Vauxhall OnStar, alongside Opel OnStar services, would cease to operate after December 31, 2020, following Groupe PSA's purchase of Vauxhall Motors and Opel from General Motors.
A new aftermarket interior rear-view mirror with a built-in OnStar module, branded as OnStar FMV, became publicly available on July 24, 2011. It provides some of the features an OEM system has, such as Automatic Crash Response, Stolen Vehicle Tracking, Turn-by-Turn Navigation, and Roadside Assistance.
Ford had "a similar system" named RESCU and it was introduced with Ford's 1996 Lincoln Continental. Ford's service is now SYNC.
The OnStar service relied on CDMA mobile phone voice and data communication, primarily via Verizon Wireless in the United States and Bell Mobility in Canada, as well as location information using GPS technology. AT&T announced the contract to replace Verizon in 2013 based on 4G technology from 2014. Drivers and passengers can use its audio interface to contact OnStar representatives for emergency services, vehicle diagnostics and directions.
The OnStar service allows users to contact OnStar call centers during an emergency. In the event of a collision, detected by airbag deployment or other sensors, Advanced Automatic Collision Notification features can automatically send information about the vehicle's condition and GPS location to OnStar call centers.