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US3825693A
(en)
|
|
Time division multiplex branch exchange
|
|
NO143953B
(no)
|
|
Svingbar innstillingsmekanisme til forbindelse av to innbyrdes bevegelige deler
|
|
US3752936A
(en)
|
|
Key telephone call distributing system
|
|
US3651271A
(en)
|
|
Circuit arrangement including a relaxation oscillator for alternately providing ringing-tone and supervisory signals to subscriber stations
|
|
US2820100A
(en)
|
|
Station identification device
|
|
SE194238C1
(enrdf_load_stackoverflow)
|
|
|
|
US3215780A
(en)
|
|
Loudspeaking intercommunication systems
|
|
US3752924A
(en)
|
|
Telephone subscriber line ring-trip detection circuit
|
|
CA1062822A
(en)
|
|
Direct station selection hold arrangement
|
|
US4660219A
(en)
|
|
Extension ringing arrangement key telephone system
|
|
US931242A
(en)
|
|
Automatic pole-changer.
|
|
JPS61121594A
(ja)
|
|
局線・回線インタフエ−ス回路
|
|
US3294922A
(en)
|
|
Operator position equipment for telephone systems
|
|
US252986A
(en)
|
|
Telephone-exchange apparatus |
|
US3175045A
(en)
|
|
Loudspeaking intercommunication system
|
|
US1778768A
(en)
|
|
Telephone-ringing system
|
|
JPH0332945B2
(enrdf_load_stackoverflow)
|
|
|
|
US931138A
(en)
|
|
Private branch intercommunicating telephone system.
|
|
US970975A
(en)
|
|
Private-branch intercommunicating telephone system.
|
|
US760399A
(en)
|
|
Selective signal system.
|
|
US1117156A
(en)
|
|
Secret telephone-exchange.
|
|
US766224A
(en)
|
|
Selective signaling system.
|
|
US709740A
(en)
|
|
Automatic telephone-exchange system and apparatus.
|
|
US1175896A
(en)
|
|
Telephone apparatus.
|
|
US1218806A
(en)
|
|
Telephone trunking system.
|