Door Entry Systems
There are different kinds of door entry systems. Most basic one is single entry point to single inner location and more advanced ones intercom systems are complex biometric systems such as voice to text machines. Nowdays ,a wide variety of security systems can be purchased, with great selection of features and levels of access. Keypad entry systems, for instance, allow access via the input of a unique code phrase or combination of numbers and characters into a keypad.
Video Entry Systems
Advance versions have a built in video camera which allows person from inside to see who is on the front entry point. Systems as these are known as video entry systems,there are preferable version and more convenient especially when there is no CCTV system in operation.