OnStar is an operating division of General Motors, an American multinational automotive company. The company offers hands free calling, vehicle security, navigation and communication services. The company's services are available on subscription basis. OnStar operates in three countries United States, China and Canada. It serves about six million customers. In 2011, the company introduced a rear-view mirror which is equipped with OEM system features such as vehicle tracking, roadside assistance and automatic vehicle crash response. OnStar uses CDMA and GPS technologies to provide its services. The vehicles are monitored 24 hours through GPS. In case of vehicle collision, the Automatic Collision Notification feature send information about the vehicle location and condition to the OnStar call centers. The postal and official address, email address and phone number cum helpline number of onstar service center is given below. The helpline of onstar service center may or may not be toll free.