BBC Radio is an operational business division and service of the state media outlet British Broadcasting Corporation (which has operated in the United Kingdom under the terms of a royal charter since 1927). The service provides national radio stations covering the majority of musical genres, as well as local radio stations covering local news, affairs and interests. It also oversees online audio content. Of the national radio stations, BBC Radio 1, 2, 3, 4 and 5 Live are all available through analogue radio (AM or FM, also BBC Radio 4 broadcasts on longwave) as well as on DAB Digital Radio and BBC Sounds. The Asian Network broadcasts on DAB and selected AM frequencies in the English Midlands. BBC Radio 1Xtra, 4 Extra, 5 Sports Extra, 6 Music and the World Service broadcast only on DAB and BBC Sounds, while Radio 1 Dance and Relax streams are available only online. All of the BBC's national radio stations broadcast from bases in London and Manchester, usually in or near to Broadcasting House or MediaCityUK. However, the BBC's network production units located in Belfast, Birmingham, Bristol, Cardiff and Glasgow also make radio programmes. The BBC's radio services began in 1922. The British Government licensed the BBC through its General Post Office, which had original control of the airwaves because they had been interpreted under law as an extension of the Post Office services. Today radio broadcasting still makes up a large part of the corporation's output – the title of the BBC's listings magazine, Radio Times, reflects this. BBC Charter On 1 January 1927, the British Broadcasting Company was succeeded in monopoly control of the airwaves by the British Broadcasting Corporation, under the terms of a royal charter. John Reith, who had been the founding managing director of the commercial company, became the first Director-General. He expounded firm principles of centralised, all-encompassing radio broadcasting, stressing programming standards and moral tone.