You can make local, domestic, and international calls with this terminal when connected to a desktop phone. Suitable for alarm systems. Compatible with GSM 850/900/1800/1900 MHz networks and works with many service providers. Simple to install and easy to maintain. A directional higher gain antenna can be connected to improve poor signal coverage. Compatible with PABX, alarm systems, recording systems, and more. Plug type: EU plug, suitable for use in countries such as Indonesia, Germany, France, Spain, and Italy. How to use this device: Step 1: Install the SIM card only when the terminal is powered off and the AC adapter is unplugged. Step 2: Connect the antenna. Use a mobile phone to locate the area with the strongest signal and place the antenna there. Avoid placing the antenna too close to the terminal to prevent signal interference. Step 3: Connect the terminal to a desktop phone. To make calls, connect the telephone line to the RJ11 phone port on the GSM terminal and the telephone set. There is one communication port on the side of the terminal, allowing connection to one desktop phone. Step 4: Connect the power adapter and turn on the power. Step 5: Wait a moment for the device to acquire a GSM signal and enter normal operation mode. Step 6: Make calls using the connected telephone set. Specifications: 1. Network support: GSM 850/900/1800/1900 MHz 2. Frequency range: - GSM 850 MHz (Transmit: 824849 MHz, Receive: 869894 MHz) - GSM 900 MHz (Transmit: 890915 MHz, Receive: 935960 MHz) - GSM 1800 MHz (Transmit: 17101785 MHz, Receive: 18051880 MHz) 3. Voltage: DC 5V12V 4. Telephone line length: 150 cm Color: White Material: Plastic Size: 120 x 85 x 28 mm Package Contents: 1 x Wireless terminal 1 x Antenna 1 x EU plug 1 x Telephone line Note: The package includes only the items listed above. Other products are not included. Lighting and display differences may cause slight variations in color between the product image and the actual item. Measurement error is +/- 13 cm.