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. This two-way audio device offers two main functions: (1) Call the device to remotely listen in on ongoing conversations. The built-in microphone has a pickup range of up to 7 meters, allowing clear audio capture within its radius. (2) The device can automatically call your phone when it detects sound, providing real-time alerts—an advanced feature 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 when sound is detected - Rechargeable via USB charging cable - Designed for legal investigative use by law enforcement or licensed professionals Specifications: - Primary function: Multi-band GSM two-way audio device - Material: Plastic - Color: As shown in image - GSM frequency bands: 850MHz, 900MHz, 1800MHz, 1900MHz - Microphone range: 5–7 meter radius - Power: Built-in 400 mAh rechargeable battery - Continuous operation time: 5–8 hours (with voice activation enabled) - Standby time: 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 differences in display settings may cause slight variations between the product color in images and the actual item. Measurement tolerances are within +/- 1–3 cm.