1) Plugging in the power adaptor. 

2) Using battery, it can works about 15 days. 

14.With Wireless unlock control ,Tamper alarm function;

15.One outdoor camera supports up to 3pcs indoor monitors and vice versa;

16.The outdoor unit with the function of tamper alarm, and if you keep pressing outdoor calling key more than 5 seconds, will turn off battery battery’s power, once again turn on power.       http://www.doorbellalarm.com/