Read the following passage about the invention of the telephone and provide a summary. "The telephone, a device that has revolutionized communication, was invented by NAME_1 in 1876. NAME_2's invention emerged from his extensive research on sound and speech, as he sought to improve the telegraph by transmitting multiple messages simultaneously. Through his experiments, NAME_2 discovered the principle of electrical undulations, which ultimately led to the development of the telephone. The first successful telephone call was made by NAME_2 to his assistant, NAME_3, on March 10, 1876, marking a milestone in human communication."