Even though the radio has been known before 1900, the first regular radio transmissions started near the end of first decade of the 20th century. Charles Herrold started broadcasting in California in 1909, but it took ten years for similar initiatives to become permanent in Europe and the Americas. The majority of first radios were using crystal sets, but in the mid-1920s they were replaced with vacuum tubes, and later with transistors. The first radio to accept advertisements back in the 1922 is thought to be "San Jose Calling", which eventually evolved into KCBS.