
Strowger step-by-step automatic telephone exchange switch, 1897-1898
1897-1898
1897-1898
circa 1956
1948-1953
1934-1935
1948
1935
circa 1891
circa 1958-1963
1888
1900
circa 1974-1975
1933
1849
1960-1980
1971
1971
1970-1990
circa 1903
1960
1954-1956
1889
1910-1912
1923
1928
1950
1910-1920
1933-1934
1914-1924
1915
1907
1902-1903
1948-1950
1951
1801-1900
1801-1900
1925
1860-1915
1801-1900
1915-1925
1890
1966-1968
1953
circa 1978
circa 1978
1956
circa 1936
1831-1870
1840-1920