This two-way GSM audio device alerts you when it detects sounds in the surrounding environment. To use, simply insert a GSM SIM card and program the device to call your phone number. You can deploy multiple units in various locations such as bedrooms, living rooms, conference rooms, or offices. Insert a SIM card into the device, and it is ready for operation. The device offers two main functions: (1) Call the device from your phone to listen in on conversations in real time. The built-in microphone has a range of up to 7 meters, allowing clear audio pickup within its radius. (2) The device automatically calls you when it detects sound, providing remote monitoring capability. This feature enhances its functionality compared to standard GSM audio devices. Key features: Audio monitoring device, Auto-dialing function, Multi-band GSM compatibility Product notes: - Automatically calls your mobile phone upon sound detection - Rechargeable via USB charging cable - Intended for legal use by law enforcement or licensed professionals for investigative purposes Specifications: - Primary Function: Multi-band GSM Two-Way Audio Device - Material: Plastic - Color: As shown in image - GSM Frequency Compatibility: 850MHz, 900MHz, 1800MHz, 1900MHz - Microphone Range: 5–7 meter radius - Power: Built-in 400 mAh rechargeable battery - With continuous operation, working time is approximately 5–8 hours - In standby mode, battery life lasts approximately 16–21 hours - Dimensions: 4.3 x 3.2 x 1.4 cm Package contents: 1 x Audio device 1 x Charging cable Note: Light reflection and display settings may cause slight color variations between the image and the actual product. Measurement tolerance is +/- 1–3 cm.