McGrath...cable systems vary widely around this big country...when ours was new IT had a decoder box that everyone had to use, and yes, all TVs hooked to it showed the same channel....now you only need a box if you suscribe to pay channels, and I 'think' they are eliminating that with digital coding, so they can charge and allow you to see what you pay for without needing the box..I have not needed a box for years, and the company gave up trying to limit # of TVs when cable-ready TVs became common...but in other areas, they still do it the old way...but with Satellite TV, and multiple cable companies (read:COMPETITION)..it is getting a little better, though a bit pricey. (More than one provider possible...but de-regulation of prices...you can't win.)