1Press the monitor button to see the outside machine, then press the intercom button to talk to the outdoor person. 2The indoor unit has the function of unlocking (this doorbell does not include the lock). 3Hands-free intercom, 5 user cards are already equipped to unlock directly. 4Outdoor unit built-in receiver, remote control can be directly unlocked. 54 kinds of unlocking methods, card, remote control, password and unlocking of indoor unit.