Door entry systems operate as either audio or video systems. An audio door entry system allows you to speak to the caller before either letting them in or releasing the door remotely via an electronic release mechanism. A video entry system operates in the same way but has the added security of allowing you to see an image of the caller.
Multi handsets can be provided for door entry systems. This allows for greater flexibility and ease of use. So for example, you may choose to have a handset in the bedroom, living room and garage, or you may find it convenient to have the option of using a handset in different areas of your business premises.