gsm sms tracker -GSM Quad Band 850/900/1800/1900MHZ - GSM listen function, - Positioning tracking function - SOS function gsm sms tracker Main function1,the first one,real ... ,SOS function8,headphone talk9,GSM listen function10,Remote network signal/battery/alarm status check11,Low battery alert12,Can set alarm interval13,frequency: 850/900 ...