Coaxial cable was invented by Herman Affel and Lloyd Espenschied at AT&T Bell Telephone Laboratories in 1929. They were trying to find an efficient way to carry the high frequencies needed for broadband communications systems. Eventually, they landed on a transmission system using a coaxial conductor; the structure reduced frequency losses and also prevented outside interference. Coaxial cable made it possible to carry thousands of simultaneous phone calls on long-distance circuits for the first time. Later, Affel worked with other engineers at Bell Labs to combine coaxial cable with microwave relays, allowing for high-volume transcontinental telephone and television transmission signals. Coaxial cable changed the face of communications all across the world and is still used for many purposes, including for cable, internet, and phone in many areas.