1、The power input of access control system is DC 12V ordinary power supply. Internal board that supports rechargeable Lion battery (3.7V) for power failure alarm (battery not included). Press the keyboard and enter the room number to call the host. 2、Up to 400 room numbers, each room number can be preset two phone numbers to call. Up to 800 phone numbers can call the system for free to trigger the onboard relay to activate the door. Even during a call, you can press the button on the phone keypad to release the visitor's door opener. 3、This system not only provides two‑way voice, and caller ID access control also allows known numbers to call the device. When the call arrives, it will immediately hang up, and if it knows the number, it will open the door. Use a mobile phone instead of a "key fob" to open the door, because up to 800 users can operate the door in this way. 4、The internal rechargeable battery (not including the battery) can be used for work, and an alarm will be issued when the power is cut off, and the battery will be automatically charged when the normal power supply works again. If the battery power is low, an alarm will also be issued. 5、Innovative waterproof lock design and stainless steel front panel. Double relay output can easily control the door opener or alarm components. When talking with visitors, remotely control the relay output by pressing the keyboard.