can’t find “the stick”

I am looking for a product that you put on your phoneline before your computer, fax, and answering machine. The one type I have seen is called “THE STICK”, it is about 5″ long and 2″ wide. It’s purpose is to determine if an incoming call is a phonecall,fax or whatever. I know it exist buy searching the net has been non-productive. I am also looking for an internet answering machine. I think this is a software program but, I am not sure. any help would be appreciated!