That gives me a “permanent, personal number” which I can point at any phones I want to. You can have filters so that particular callers go to particular phones. I could have anyone from work that is calling forward to my work cell, while friends and family go to my personal cell. You can block callers or have some go straight to voice mail.
I you enable it, it transcribes voice mail messages into text like email and you can read your voice mail just like email. There's a little button where you can play the message, too. You can send a reply via SMS (TXT) or call back if you are using the web interface from a cell phone.
There's a listen-in feature, so when your phone rings, the computer voice tells you who is calling. You can then listen in to their voice mail just like an old-fashioned answering machine and “pick up” on the call if you wish.
If you are talking to someone, say on a desk phone at work, you can press * and transfer the call to another phone in your list, like your cell phone. Your cell will ring and, when you anwser, the call is transferred, and the caller doesn't even know (except they may hear your cell ring).