Feature: 1. With dual alarm input ports, can provide emergency alarms in some places, and you can connect the existing sensors or any other relay output type sensors to it for security alarms. 2. Built‑in backup rechargeable battery (3.7V, 1000mA), used for power failure alarm. Through the call button, call the internal stored number for intercom. The working voltage is AC/DC12‑24V. Key lock for safe installation and easy maintenance. Rainproof design of the whole box. GSM‑HELP is not only a simple GSM emergency call phone, but also can be used as a "site monitoring function" and a security alarm box. 3. Very simple to install and plug in, the settings are started by SMS. 5 calling numbers can be stored in advance, If the first number is not able to be connected, the next number will be called in sequence. Not only can you make a call through the button, but you can also set a specific number to make an active call, 3 working modes, call answering mode, monitoring mode, and direct call connection mode. 4. The internal rechargeable battery can be connected to work when the power is off. The battery will be automatically charged when the normal power supply works again. If the battery power is low, it will also send an alarm. 5. Very suitable for private houses or public emergency calls, suitable for unmanned cab offices, taxi help calling site, door phones to talk to visitors or any outdoor place. The user only needs to press the button, and then the box will dial the number (two numbers are preset in the memory), and then you can pick up the phone to talk to the visitor. Specification: Item Type: Handfree Audio Intercom Alarm Material: Hard ABS Plastic Color: BlackPower Input: AC / DC12-24V GSM Frequency: 850/900/1800/1900MHz Battery Capacity: 1000mAh (built-in) How to Use: 1. The product requires wiring. 2. Insert a 2G mobile phone card (NOT Includes the SIM Card) into the product. 3. Pair and connect with the mobile phone. 4. The product can be controlled by mobile phone.. Package List: 1 x Handfree Audio Intercom Alarm1 x Antenna2 x Keys1 x Manual