US4068101A
(en )
1978-01-10
Method and apparatus for the automatic communication of two telephone subscribers
US2909607A
(en )
1959-10-20
Automatic telephone system with automatic transfer
BE460754A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
US2815404A
(en )
1957-12-03
Connection for automatic ring signal
US1558872A
(en )
1925-10-27
Telephone system
CH198010A
(fr )
1938-05-31
Installation téléphonique à batterie centrale.
US1930921A
(en )
1933-10-17
Telephone system
US1364106A
(en )
1921-01-04
Automatic telephone system
BE391837A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
US938039A
(en )
1909-10-26
Apparatus and system for measuring telephone service.
US1901179A
(en )
1933-03-14
Automatic telephone system
US1393946A
(en )
1921-10-18
Telephone-exchange system
US1722538A
(en )
1929-07-30
Automatic telephone system
US1502916A
(en )
1924-07-29
Automatic telephone system
DK141799B
(da )
1980-06-16
Abonnentkobling til telekommunikationsanlæg.
BE341584A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
BE455605A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
BE514857A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
BE383771A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
CH94572A
(fr )
1922-05-01
Installation pour bureaux centraux téléphoniques automatiques.
PL39271B1
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
1955-12-15
GB263210A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
BE349415A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
BE358694A
(GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html )
GB254790A
(en )
1926-07-06
Improvements in or relating to telephone systems