The connection between the two major fascist regimes of the XX Century and the new forms of mass communication has been solidified in the common mind – the new mass media being so integral to the regimes and to their pervasive propaganda apparatus – that one would have a hard time picturing fascism without parades, marches, uniforms and flags, without newsreels and announcers, sport events, cinema, without some form of artistic expression; and without radio broadcasting, of course.

The Regime penetrating every facet of social and private existence, from one's readings, to their holidays, free time, entertainment. Such a consolidated image is at the same time true and misleading. True because the Regime did exert its influence and control on public and private life, and especially on those aspects that for their novelty and infrastructural demands made state initiative by default superior to private one. Misleading because this penetration, this control, this being “everything within the Regime, nothing outside of it” was exactly the image the Fascist Regime in its finished (or half-finished) form wanted to give of itself: its legacy, its perpetual form, the eternal march, the never ending fires, the countless youthful scores with their eyes lost into the horizon.

The idea of an authority that surrounds you in every aspect of your life, that you can only exist within, that one and only provides you self realization through the acceptance of your subordination. That's an idea that might cause some discomfort. But that's only if you think of yourself outside of fascism; and why on earth would you think yourself outside of fascism?

But with that, of course, we are still looking at the image the Regime built for itself; which is true and misleading at the same time. True because it's the idea of fascism created by fascism, and one should take the Regime's openly expressed intentions into account. Misleading because we know that the Regime was far less in control than it claimed to be, far less pervasive, far less unitary, far less grandiose and mighty; and also because not everything in the regime was intention – not everything that happened within fascism was a deliberate product of fascism, and intention should always be considered in its organic (and at times conflicting) relations with the structures the fascist regime inherited or developed independently or alternative to a unitary volition.

The large propaganda apparatus worked at building consensus as much as it worked at hiding dissent, masking indifference, reclaiming to the Regime all the achievements of human labor and ingenuity; in short to create (or conjure) the unity of things apart. To this feat, radio, cinema, the good old press were essential. And somewhat expensive. And new. And to some extent their novelty, their cost, their technological advancement worked as the better half of their overall impression on the people. The Regime didn't have to persuade through the fascist radio broadcast, through the newsreels, through the movies, the songs, the sportive triumphs: it was enough for those things to exists, and to exist within the Regime – not that they could exist otherwise. Radio broadcasts weren't fascist just because they spoke of the regime's achievements – which they did obviously and increasingly so – but because the radio was an emanation of the Regime. Persuasion had both an intentional and a structural dimension.

But there was intent in it. The first official radio transmission (a quartet of Haydn – op. 7) ended with the fascist song Giovinezza - a song of the black shirts, re-purposed into an official anthem of the Fascist Party – it wasn't of course by chance: the radio broadcast was provided by the new founded Ministry of Communications, a “fascist” ministry led by Costanzo Ciano (Galeazzo's father). It was October 6^th 1924. Two years after Mussolini had been appointed Prime Minister. And that answers part of your question. As for Italian Fascism, which will be my only focus here, the radio played no role in destabilizing the previous political system (not in the context of any abrupt transition – that would anyway warrant a deeper inquiry: see for instance Vivarelli, R. Il fallimento del liberalismo as well as a good number of recent English literature on the idea of fascism as breach vs. continuity with the previous liberal state); and in fact one might make a case that all media outlets (press included) were less impactful that one might expect in heralding the rise of fascism.

 

Observed Alberto Monticone, in his preface to his study: Il fascismo al microfono – radio e politica in Italia (1924-1945) (I rely on this work from 1978 heavily in the following – more recent works are probably available but I consider his general outlook on the problem to provide deeper insight than other works more specifically focused on the propaganda aspect) that

the radiophonic medium is examined here as a political instrument, in a manner not dissimilar from finances, army, press, diplomacy and any other form of politics put into motion during [the fascist years]. [This approach] operates under the assumption […] that fascism made use of the radio – that is both the radio institutions and infrastructure, the related economic and industrial background, and the broadcast content – to make politics, its own politics: that is, according to times, foreign policy, war policy, agrarian, cultural, public opinion, party, military, religious policy.

The purpose therefore would be to re-evaluate the role of the radio within the Fascist Regime, as historiography was naturally drawn to consider the development of national radio broadcast in the 1920s and 1930s under the most obvious angle of fascist propaganda alone (something that also results from what to my knowledge is still a lack of systematic archival treatment of the radio materials from the fascist era, with the result that many contributions rely very much on their own personal focus for research purpose, building from the legitimate anti-fascist angle of the first published works of Salvatorelli and Galante-Garrone); while more broadly speaking the role of the fascist radio within the fascist regime (and this includes its role in creating consensus) wasn't limited to the use the regime choose to make of it. And the relation between the new mass communications and the Regime was more organic than a pure matter of control.

As for the function of the radio within the Regime, Monticone attempts a periodization pointing out that

during the first ten years of fascism, both for the relative lack of interest towards the radiophonic medium and for the limited number of subscribers, the Italian radio took the form of an elite phenomenon, offering examples of a bourgeois-aristocratic culture of XIX Century imprint […] It's with the early 1930s that a significant effort took place […] The small-bourgeois Italy, humanistic and rhetoric, patriotic and roman became the specimen of the average audience […] in a planned education of the radio audience within a nationalistic climate, closer to pre-fascist culture than to the growing imperialistic aspirations. Political action through the radio showed a pattern of significant delay [in comparison to the Regime's ambition, as well as] an attempt, largely failed, to reach those large portions of the country, that neither the liberal culture nor education had been able to touch. […] And further ahead, in the immediate proximity of the war, it was the pattern of the canzonette and radiophonic evasion to mark the peculiar relations between the Regime and the social and political reality of the country.