Teltrend, Inc.

Van Nguyen

Frank X Garcia

Earl L Smith

A digital loop carrier system that more conveniently passes a flash-hook signal while still allowing open-switching-intervals (loop current feed open intervals) with a floating ground central office switch interface. The carrier system includes both an office loop and a customer loop. The interface includes both an office loop switch and controller. The controller regulates the operation of the switch and also regulates whether the customer loop should be open or closed. When the office loop is not grounded, but current was detected by the controller in the office loop prior to the controller opening the office loop, the controller waits a predetermined interval after opening the office loop before opening the customer loop and terminating the call.

Floating digital loop carrier telephone interface

A transmit path limiting circuit that allows other equipment, such as a caller identification device, to more readily decipher information signals on a telephone line. The circuit includes a ring detector, register, and controller. The ring detector senses that a call is incoming to the telephone and responsively provides an initiation signal. The register normally transmits outgoing signals from the telephone to the telephone network. After receiving the initiation signal, however, the controller enables the register, for a predetermined interval, to transmit a quiet code in lieu of any signal being transmitted from the telephone. Consequently, reflected noise is lowered during the predetermined interval, so that the caller identification box may more easily interpret data on the telephone line.

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Wheaton, IL, United States of America

Van Nguyen