This two way GSM audio device calls you when it detects sounds around its vicinity. How awesome is that? Simply insert a GSM SIM card and program it to your desired phone number for call back and now you're in the businessTrying to find out the truth about what's being said behind your back? Now you can from a distance. You can even place several of these audio devices and set them up at your desired locations like the bedroom, living room, conference room or office. Just insert a SIM card into the audio device and your bug is active and ready for actionThis two-way audio device comes with two amazing functions:(1) Make a call to the audio device and you can instantly listen in to conversationsThe built-in microphone works up to a 7 meter radius, so set this bug up wherever you want(2) Allows the audio device to call you when it hears people talkingThis feature makes it much more advanced than other GSM audio bugs on the market today.Hot spots:Audio GadgetAuto Dialing optionTri-Band GSM Audio DeviceProduct Notes When it detects sound, the bug will call your cell phoneYou can recharge the audio device by connecting the USB charger cable to the power chargerThis product is being sold as an investigative tools for law enforcement or licensed investigators. Anyone else ordering this device should only be ordering it as a simple toy since MANY COUNTRIES STRICTLY PROHIBIT OWNERSHIP OF DEVICES.Important Note: You are solely responsible for finding out whether this product is legal to import and/or use in your country. We will send you the products you order and cannot accept any liability for customs issues or any implications of your ownership or usage of this device.Specifications:Primary Function: Tri-band GSM Two-Way Audio DeviceMaterials: Molded PlasticColor: BlackGSM Frequency Compatibility: Tri-band (850MHz,900MHz, 1800MHz, 1900MHz)Microphone Range: 5-7 meter radiusPower: Built In 400 mAh Rechargeable Li-ion BatteryTurn on the voice control function and the expected continuous working time is 5-8 daysOnly the positioning function is expected to last for 16-21 daysDimensions: 4.3x 3.2 x 1.4(cm)Package Included:1 Listener1 Charging cable1 Instructions