IS90B6
(en )
1937-04-19
Landline and submarine phones with high voice attenuation in connection with amplifiers
FR691894A
(en )
1930-10-28
Telephone and radiotelephone membrane
DK39927C
(en )
1929-03-18
Cable with Continuously Increased Self-Induction and Balancing for Cross Speech.
ES119361A1
(en )
1930-09-16
Improvements in procedures and telecommunication devices.
DK46426C
(en )
1932-11-07
Device for Receiving and Reproducing Sound.
FR724426A
(en )
1932-04-27
Improvements to telephone systems and similar transmission systems
ES99104A1
(en )
1926-11-01
Improvements in radiotelegraph and telephone communications.
ES116507A1
(en )
1930-02-16
Improvements in networks or telephone lines.
ES120151A1
(en )
1930-11-16
Improvements in the procedures of impressed and reproduction of sounds.
DK36954C
(en )
1926-12-27
Procedure for Reducing Cross Speech in Telephone Cables and Metal Cases for Carrying Out the Procedure.
ES92865A1
(en )
1925-06-01
Improvements in telephone and radiotelephony receivers.
FR39522E
(en )
1931-11-30
Further training in gas-filled photoelectric cells
FR613256A
(en )
1926-11-13
Further training in telephone headsets
ES117322A1
(en )
1930-05-01
Improvements in telephone devices.
FR674868A
(en )
1930-02-03
Improvement in phonographs and more especially portable phonographs
FR728168A
(en )
1932-06-30
Telephone amplifier
ES121046A1
(en )
1931-01-16
Improvements in phonograph records and devices.
AT132897B
(en )
1933-04-25
Circuit arrangement for telephone systems with connection devices consisting of setting and voice dialers.
DK39685C
(en )
1929-01-07
Procedure for Reducing Cross Speech and Listening in Telephone Double and Duplex Cables.
CA297546A
(en )
1930-02-18
Telephone silencer
FR710851A
(en )
1931-08-31
Combined rocker and speaker
FR688240A
(en )
1930-08-20
Talking Cinema Improvements
ES124424A1
(en )
1931-11-16
Improvements in telephonic and similar transmission systems.
ES121207A1
(en )
1931-02-01
Improvements in radiotelephone and acoustic intercommunication equipment.
DK39558C
(en )
1928-12-03
Procedure for Abolition of Cross Speech in Telephone Cables.