Patent classifications
H
ELECTRICITY
Load children
H04
ELECTRIC COMMUNICATION TECHNIQUE
Load children
H04M
TELEPHONIC COMMUNICATION
Load children
9/00
Arrangements for interconnection not involving centralised switching
Load children Filter patents View analytics View as hierarchy
H04M9/08
Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic
Load children Filter patents View analytics View as hierarchy
H04M9/10
with switching of direction of transmission by voice frequency
Filter patents View analytics View as hierarchy