Features: The front panel is installed without screw locking for easy installation. Dual relay output for easy control of door openers or alarm components. Press the remote control relay output through the keyboard while talking to the visitor. The device produces high quality audio calls up to 2 numbers. If the person answering the call wishes to allow access, they simply release the on-board relay by pressing the button on the handset. Allow 200 phone numbers to make free calls to trigger onboard relays. This system provides two-way voice, Caller ID access control allows a known number to call the device. When the call arrives, it is immediately discarded, and if the number is known, the door or door is released. It is suitable for mobile phones, and up to 200 users can operate the gate in this way. Even during a call, you can press the button on the phone's keypad to open the door for the visitor. The battery can be reconnected internally (not included) for operation and alarms during a power outage, and the battery will automatically fail when the normal power supply is working again. It also alerts if the battery is low.Specification: Condition: Brand New Color: Shown as Picture Material: Stainless Steel GSM Frequency: 850/900/1800/1900MHz Power input: AC / DC12V-24V Battery: 3.7V, 1000mA(Excluded)Package List: 1 x Gsm-house Box 1 x Antenna 2 x Key 1 x USB Data Cable 1 x USB Program Adapter