All radio in the USSR was broadcast by the state. Radio programs came to listeners not only through the airwaves but also through wire transmission. Speakers connected to the wire networks were always far more common than regular radio receivers: in large cities they were found in almost every apartment. Besides that, programs were transmitted through loudspeakers in the streets.
From the middle of the 1960s on, all new construction included the obligatory radio cable running into every apartment. The wire ended with an outlet into which it was possible to plug headphones or a radio speaker. In the last decades of the Soviet regime, there was not only one but three channels; in order to choose between the three available programs, one needed to hook up a special three-channel speaker.
The monthly charge for radio reception was small. People received radio broadcasts of news, music, and literary programs at almost no cost. In contrast to regular radio transmissions by air, the radio speaker allowed near complete control over what the country's citizens could listen to (and thus it was that during the war, regular radio receivers were confiscated).
Cable radio also played a critical role in civil defense, as a warning system for the population.
See image of various models of radio speakers at: http://www.starinism.ru/museum/rtochka.htm