... A means add number) 4 sos numbers are available for the device. For example: SOS, A,13910283465,13910283465,13910283465,13910283465# ... number cellphone dial device, ringing for 10s, it will enter voice monitoring status. At this time, caller can monitoring the ... you can activate GPS positioning. The precision is aroung 10m. Notice: The sim card should activate GPRS function. GTK920 long standby time ...