In 1892 Bell controlled 240,000 telephones. But the independents were coming on fast, especially by using better technology. The first automatic dial system began operating that year in La Porte, Indiana. The central office switch worked in concert with a similar switch at the subscriber's home, operated by push buttons. Patented in 1891 by Almon B. Strowger, this Step by Step or SXS system, replaced the switchboard operator for placing local calls. People could dial the number themselves. The first automatic commercial exchange began operating in La Porte, Indiana in 1892.