... sensor optional.2 SD Card slots optional,VOIPl Built-in wireless module like 3G (EVDO, WCDMA,HSPA, HSDPA, TD-SCDMA…), GPRS…optional ... to induce the vehicle X, Y, Z axis3G,WIFI Wireless transmissionBuilt-in wireless module optional. Such as 3G EVDO, HSPA, HSDPA, WCDMA…GPRS ...