Like all sounds, speech also consists of sound waves. The mouthpiece of the telephone has a microphone, which converts the spoken sounds into electrical current. The transmission of electric current is done through wires. In the earpiece, the electric current is converted back to sound waves. Earlier, the wires were made of copper, but today telephonic conversations are transmitted through glass fibre cables or even via satellite connections. Telephone calls over long distances were earlier possible only through telephone operators. Since 1970, however, we can make overseas calls directly. The telephone was invented by Graham Bell, who applied for its patent in 1876.
