WebView - MyView Member Interface

I am working on the interface for MyView a new Micro Key Solutions product in the WebView Web Solutions line. I am developing the member interface right now. My issue is one of security.

What do you do to make sure you are actually talking to a customer and not someone trying to gain access to an alarm system? Meaning when a customer calls and asks to change passwords or add new users what do you do, to make sure they are authorized to do so?

Your insight would be greatly appreciated.