One of the first signals of significant power that carried voice and music was accomplished in 1906 by Reginald Fessenden when he made a Christmas Eve broadcast to ships at sea from Massachusetts. He played "O Holy Night" on his violin and read passages from the Bible. However, his financial backers lost interest in the project, leaving others to take the next steps. Early on, the concept of broadcasting was new and unusual—with telegraphs, communication had been one-to-one, not one-to-many. Sending out one-way messages to multiple receivers didn't seem to have much practical use.
Charles Herrold of San Jose, California sent out broadcasts as early as April 1909 from his Herrold School electronics institute in downtown San Jose, using the identification San Jose Calling, and then a variety of different call signs as the Department of Commerce began to regulate radio. His station was first called FN, then SJN. By 1912, the United States government began requiring radio operators to obtain licenses to send out signals. Herrold received licenses for 6XF and 6XE (a mobile transmitter) in 1916.
He was on the air daily for nearly a decade when World War I interrupted operations. After the war, the Herrold operation in San Jose received the call sign KQW in 1923. Today, the lineage of that continues as KCBS, a CBS-owned station in San Francisco.