When did bell telephone start in US?

The Bell Telephone Company was founded in 1878 by Alexander Graham Bell's father-in-law Gardiner Greene Hubbard, who also helped organize a sister company - the New England Telephone and Telegraph Company. The two companies merged in 1879 to form the National Bell Telephone Company, which in 1880 merged with others to form the American Bell Telephone Company, which in turn became the American Telephone & Telegraph Company (AT&T).