DIFF Subgroup
H04M 9/10 with switching of direction of transmission by voice frequency
Introduced: September 1968
Full Title
Arrangements for interconnection not involving centralised switching > Two-way loud-speaking telephone systems with means for conditioning the signal, e.g. for suppressing echoes for one or both directions of traffic > with switching of direction of transmission by voice frequency
No child classifications to compare. This is a leaf node in both IPC and CPC.