Alexander Graham Bell was an eminent scientist, inventor, engineer and innovator. Throughout his life, Bell had been interested in the education of deaf people, as both his mother and his wife were deaf. This interest led to invent the microphone and in 1876, his 'Electrical Speech Machine', which we now call a telephone.
What followed after that is history. Bell Telephone Company (later AT&T) was set up in 1877, which grew to be one of the largest telephone companies in the world