It is not necessary to have an internet connection to use the built in CD player or FM tuner of the RCX-1500, as well as the Aux 1, Aux 2 or front USB inputs. However, all other inputs do require a working internet connection. Do note that while the FM tuner does not draw its signal from the internet, it is a part of the internet radio module therefore will not start if one of the USB dongles is not physically connected to the unit.