... ( 900MHz,1800MHz OR 850MHz ,900MHz,1800MHz, 1900MHz) 2. GSM cell phone carrier/ 3. Friendly human voice ... , 1900MHz) (4 frequency add for $ 13.00)2. GSM cell phone carrier/3. Friendly human voice instruction4 ... Sensitivity of shock sensor adjustable10. Check system status by telephone/13. False alarm trigger prevention11. Status LED indicator/ ... & extra cost)& extra cost) 2012 sell CAR ALARM SYSTEM