In 1920, the American Telephone & Telegraph Company began to develop vacuum-tube radio transmitters for commercial services. Its experimental station, 2XJ, located at Deal Beach, New Jersey and operated by AT&T's Western Electric subsidiary, began transmitting test programs in March, 1920, which included occasional entertainment offerings intended for a general audience.

The transmitters designed at Deal Beach were quickly introduced into commercial service, beginning with a telephone link between Catalina Island, California and the mainland that went into service in July, 1920. Western Electric also began selling transmitters to broadcasting stations, the first of which went into operation in January, 1922, at the Detroit News' station, WBL, which three months later changed its callsign to WWJ.

Radio News, October, 1920, page 258: (1921 photograph of 2XJ facilities is from Commercial Broadcasting Pioneer, by William Peck Banning, 1946)

Bright  Outlook  for  Amateur  Radio
    Since the war interest in radio telegraphy and telephony has increased to the extent that there is hardly a square mile in the populated sections of this country that does not boast of at least one antennae system.
    This interest is partially due to the great number of men who received radio training in the Signal Corps of Naval Radio branches of the service, but possibly due in a greater degree to the very material increase in the range and efficiency of present-day wireless equipment
    As the number of radio devotees increases an added incentive is given to the pleasure of owning and operating one's own station. The American Radio Relay League, an organization composed solely of amateur operators, has undertaken to provide the opportunity of sending a message to anyone in this country without charge. And now, on any evening, hundreds of these "feeless" messages can be heard hurrying to their respective destinations via the obliging amateur.
    The radio telephone, once an instrument of conjecture, can now be found in almost every progressive station. The amateur station, unlike the commercial station, is unmolested by the patent situation, and for this reason amateur equipment rivals that of the most advanced commercial installation.
    Dancing by radio is the latest fad; by the use of a radiophone and a phonograph at the transmitting end and a sensitive radio receiver equipped with an amplifier, and a loud-speaking horn at the receiving end music can be heard all over the hall. The station transmitting may be hundreds of miles away, but the notes are as clear and as well modulated as if the orchestra were in the same room!
    Wireless concerts also give added pleasure to the owner of radio-receiving apparatus. The Western Electric Company experimental station at Deal Beach, N. J., has provided entertainment of this nature for the past few months. The program includes selections by famous artists, band music, humorous pieces and lectures. This concert is given every Tuesday evening, starting at 10 o'clock and continuing until midnight, and can be heard for hundreds of miles in every direction.
    The radio art is ever new. Although its development has been phenomenal, the next five years will see many radical changes, all affording greater efficiency and creating greater interest. Boston Post.