You can make local, domestic, and international calls with this terminal by connecting a desktop phone and a SIM card. Suitable for alarm systems. Compatible with GSM 85090018001900 MHz networks and works with many service providers. Simple to install and easy to maintain. A directional high-gain antenna can be connected to improve signal coverage in areas with weak reception. 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 a SIM card Insert the SIM card only when the terminal is powered off and the AC adapter is disconnected. Step 2: Connect the antenna Use a mobile phone to locate the area with the strongest signal, then place the antenna there. Avoid placing the antenna too close to the terminal, as it may interfere with signal performance. Step 3: Connect your 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 device. 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 85090018001900 MHz 2. Frequency range: - GSM 850 MHz (Transmits: 824849 MHz, Receives: 869894 MHz) - GSM 900 MHz (Transmits: 890915 MHz, Receives: 935960 MHz) - GSM 1800 MHz (Transmits: 17101785 MHz, Receives: 18051880 MHz) 3. Voltage: DC 5V12V 4. Telephone line length: 150 cm Color: White Material: Plastic Dimensions: 120 x 85 x 28 mm Power Input: AC 220V Package Contents: 1 x Wireless terminal 1 x Antenna 1 x EU plug 1 x Telephone line