Spy GSM Sim Phone Device Description
Put a SIM card in the device,just phone it then you could hear the surrounding.
1: Microphone range: about 20 Meters (diameter)
2: Stand-by time: 3-5 days (using voice control function)
3: 6-15 days ( don’t use voice control function)
4: 30-40 hours (flashlight available)
5: call back option