Earthlink Cable → Re: [Modem] Retain TW cable/Internet with cancellation

I'm curious about a different aspect of this question. I have never thought about it, but how portable are cable modems? That is, I know I can take my cable modem move it a few blocks away to another active TW line and it will work as long as no hicut filters are on the line itself. I assume that's what is going on with the original poster.) Obviously, the cable company can't discriminate the physical location of a device as long as it's connected to the same local node. I guess the real question I'm asking is what kind of checking (if any) does the service provider do to associate the modem's general location with the modem's "proper" location?