Automatic echo cancellation for an integrated services digital n

Details Automatic echo cancellation for an integrated services digital n Automatic echo cancellation for an integrated services digital n

1994-10-04

1997-05-20

Zele, Krista M.

Telephonic communications

Subscriber line or transmission line interface

Network interface device

379406, 379408, 379411, H04M 900, H04B 320

Patent

active

056319584

ABSTRACT:
An echo canceler is connected to an ISDN Primary Rate Interface. The echo canceler is provided with an activation processor for monitoring call control messages on the D-channel and for selectively enabling or disabling echo cancellation on any of the B-channels in response to information contained within the call control messages. In particular, the activation processor decides whether to enable cancellation depending upon the Information Transfer Capability and Protocol Identification fields of the Bearer Capability portion of a call SETUP message. Additionally, the Channel Identification field of the SETUP message is used to identify the B-channel or channels affected by the SETUP message. When a channel is released, the activation processor maintains enabled echo cancellation as the default condition of the released channel. Other signal processing functions can be controlled by the activation processor in a similar manner.

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K. Tanzillo, "Echo is nagging problem in primary rate private network", Communications News, Oct., 1994 (p. 49).
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