 During the war, vacuum tube radio transmitters had been developed that made audio transmissions practical.Reynolds began work with the U.S. Forestry Service to evaluate the practicality of using radiotelephones to aid department communication.He also took advantage of the equipment provided by the Forestry service to experiment with entertainment broadcasts, and one of his first radiotelephone tests, in May 1920, provided musical selections for a dance held by students at a local high school.