|
GB421059A
(en)
|
|
Improvements in devices for recording and reproducing telephonic messages
|
|
BE454021A
(enrdf_load_stackoverflow)
|
|
|
|
US1647796A
(en)
|
|
Telephone system
|
|
US2295032A
(en)
|
|
Communication exchange system
|
|
US2025145A
(en)
|
|
Transmission system
|
|
US2087398A
(en)
|
|
Automatic switch for use in telephone or like systems
|
|
US1727137A
(en)
|
|
Automatic telephone system
|
|
US2745903A
(en)
|
|
Signaling system
|
|
US2036316A
(en)
|
|
Telephone system
|
|
US2815404A
(en)
|
|
Connection for automatic ring signal
|
|
US1557609A
(en)
|
|
Printing-telegraph exchange system |
|
US1107135A
(en)
|
|
Telephone-exchange system and apparatus.
|
|
US1521821A
(en)
|
|
Repeater for automatic telephone systems
|
|
US2862058A
(en)
|
|
Selector systems
|
|
US1963747A
(en)
|
|
Telephone system |
|
US1505715A
(en)
|
|
Telephone system
|
|
US1857848A
(en)
|
|
Communication system
|
|
US1132107A
(en)
|
|
Automatic telephone system.
|
|
US1720107A
(en)
|
|
Impulse-repeating device for automatic and semiautomatic telephoneexchange systems
|
|
US1939725A
(en)
|
|
Transmission circuits
|
|
US1002878A
(en)
|
|
Party-line telephone system.
|
|
US1722538A
(en)
|
|
Automatic telephone system
|
|
US1339575A
(en)
|
|
Machine-switching telephone-exchange system
|
|
US2996582A
(en)
|
|
Discriminating trunk circuit
|
|
US1557991A
(en)
|
|
Automatic telephone-exchange system
|