Appeal No. 2002-1241
Application No. 08/883,141
Digital Network (ISDN) data transmissions do not require echo cancellation. Thus, digital echo
cancellers used in conventional telephone networks must be disabled when sending and receiving
data and other digital data transmissions using ISDN lines.
While the prior art has addressed this problem, for example, by maintaining individual
echo cancellers in a disabled state and merely passing voice signal transmissions through without
applying echo cancellation, because each echo canceller is dedicated to a particular voice signal
line, a significant percentage of echo cancelling equipment remains unused at all times.
Accordingly, the instant invention provides an echo canceller system for use in a digital
telephone transmission system in which echo cancellers are pooled and selectively interconnected
by call processing control through a pool switch matrix to individual transmission lines only if
the line requires echo cancellation. This is said to permit efficient use of the echo cancellers on
an as-needed basis, so a relatively small number of echo cancellers can effectively service a
relatively large number of individual transmission lines.
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