Converter boxes do not allow viewers to watch free cable. Converter boxes are used to transform the electronic signal sent from a cable company into an analog RF signal that can be detected and displayed on a television. Receiving cable broadcasting requires a monthly subscription to a cable service.
In the early days of television, signals were broadcast over the airwaves in a similar fashion to radio. Televisions used antennae to receive the signal, which was directly displayed on the screen. There was no charge for this service, just as listening to the radio was free. The development of cable television allowed the information to be sent electronically through physical cables across the country. This new type of programming came with subscription models and fees, though traditional "broadcast" channels still offered free use through air signals.
As many televisions were not equipped to decode this electronic signals, converter boxes were created to handle the transformation.Over time, new televisions were developed with built in conversion technology, making converter boxes nearly obsolete. However, the advent of pay-per-view channels and digital cable introduced a new set of signals and protocols, renewing the use of special converter boxes.
In 2009, the air broadcast system was phased out in favor of fully digital transmissions. While still free, this type of programming required special receivers to decode the signals.