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 business!  This two-way audio device comes with two amazing functions: (1) Make a call to the audio device and you can instantly listen in to conversations! The 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 talking! This feature makes it much more advanced than other GSM audio bugs on the market today. Product Notes ： When it detects sound, the bug will call your cell phone You can recharge the audio device by connecting the USB charger cable to the power charger This 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: GSM Frequency Compatibility: Tri-band (850MHz,900MHz, 1800MHz, 1900MHz) Microphone Range: 5-7 meter radius Power: Built In 400 mAh Rechargeable Li-ion Battery Turn on the voice control function and the expected continuous working time is 5-8 days Only the positioning function is expected to last for 16-21 days Dimensions: 4.3x 3.2 x 1.4(cm) Package Included: 1 * Listener 1 * Charging cable 1 * Instructions