US2291481A
(en )
1942-07-28
Telephone system
GB211662A
(enrdf_load_stackoverflow )
GB220923A
(en )
1925-06-12
Improvements in or relating to telephone systems
GB211639A
(en )
1924-02-28
Improvements in or relating to telephone systems
US2036055A
(en )
1936-03-31
Telephone system
GB209017A
(en )
1924-07-24
Improvements in or relating to telephone systems
US1935910A
(en )
1933-11-21
Telephone system
GB354858A
(en )
1931-08-20
Improvements in or relating to telephone systems
GB329366A
(en )
1930-05-14
Improvements in or relating to automatic or semi-automatic telephone systems
US2854515A
(en )
1958-09-30
Drop back selector circuit
GB430295A
(en )
1935-06-17
Improvements in telegraph exchange systems
US1765619A
(en )
1930-06-24
Party-line telephone system
GB325019A
(en )
1930-02-13
Improvements in or relating to telephone systems
US1438758A
(en )
1922-12-12
Machine switching device
US3140353A
(en )
1964-07-07
Party line identification system
US2834834A
(en )
1958-05-13
Circuit arrangement for reducing the call losses in telephone systems with registers
US2933561A
(en )
1960-04-19
Two-station party line switching in telephone systems
US2935570A
(en )
1960-05-03
Telephone systems
US2785237A
(en )
1957-03-12
Howler control circuit
GB322241A
(en )
1929-12-05
Improvements in or relating to automatic and semi-automatic telephone exchange systems
GB230006A
(en )
1925-10-08
Improvements in or relating to telephone systems
GB324675A
(en )
1930-01-31
Improvements in automatic or semi-automatic telephone systems
GB367936A
(en )
1932-03-03
Improvements in or relating to telephone or like systems
GB380479A
(en )
1932-09-13
Improvements relating to telephone systems
GB320380A
(en )
1929-10-11
Improvements in and relating to automatic or semi-automatic telephone systems