... , you can set 5 phone number in SIM card, be sure in first (1, 2, 3, 4, 5) position in the SIM card, which 5 ... your SIM card number, And inter password (1 2 3 4 #) to monitor the voice in alarm place to hear what is happened. Then ... you wand to add Wireless Infra Red Detector ,door sensor, or remote controller in the system, you can open the power of Wireless Wireless GSM Alarm System