回复：请教： Home Security System

- ADT system or any alarm systems: Generate alarms and call 911 when breaking in is detected. But they do not take pictures/video. You need to pay monthly fee. You need a telephone line or additional fees will be charged.

- Camera Surveillance System: Take pictures/video only. You don't pay monthly fee and you don't need to have a telephone line. If you just want to see/record what happens around/in your house, a camera system is enough.