|
US2572027A
(en)
|
|
Relay set-subscriber's lockout circuit
|
|
US2302587A
(en)
|
|
Telephone trunking system
|
|
US2292371A
(en)
|
|
Repeater circuit
|
|
US3035123A
(en)
|
|
Party line telephone circuit
|
|
US4283603A
(en)
|
|
On-hook/off-hook status check circuit
|
|
US1040636A
(en)
|
|
Telephony.
|
|
US1194959A
(en)
|
|
Baldi turri |
|
US2744966A
(en)
|
|
Intercommunication system
|
|
US2009470A
(en)
|
|
Selective talking and ringing telephone system
|
|
JPS584508B2
(ja)
|
|
カニユウシヤデンワソウチ
|
|
US2210739A
(en)
|
|
Through supervision system
|
|
US1747833A
(en)
|
|
Telephone-switchboard system
|
|
US1329004A
(en)
|
|
Telephone-exchange system
|
|
US1881669A
(en)
|
|
Telephone system
|
|
US1942487A
(en)
|
|
Telephone system
|
|
US1298588A
(en)
|
|
Telephone system.
|
|
US2568138A
(en)
|
|
Combined line and tripping relay circuit for telephone lines
|
|
US1320716A
(en)
|
|
A corpora |
|
US1326546A
(en)
|
|
Telephone-exchange system.
|
|
US878265A
(en)
|
|
Automatic trunking system.
|
|
US984686A
(en)
|
|
Intercommunicating telephone system.
|
|
US1504337A
(en)
|
|
Telephone system
|
|
US1298414A
(en)
|
|
Telephone system.
|
|
US1364162A
(en)
|
|
Telephone-exchange system
|
|
US1312795A
(en)
|
|
Telephone-exchange system |