Lockout device for preventing telephone eavesdropping from an extension device, and method
First Claim
1. A local communication coder for linking between a local telephone and a telecommunication system, and responsive to an in-coming wait signal from a cooperating remote communication coder linked to the telecommunication system, for enabling the local coder and the remote coder to encode and decode communications, and for locking out any cooperating extension communication coders linked to the telecommunication system from encoding and decoding communications, the local coder comprising:
- wait means for advancing the local coder from a normal mode of operation during which out-going communications from the local coder are not encoded and in-coming communications to the local coder are not decoded, to a wait mode of operation during which the local coder listens for the wait signal from the remote coder;
listen delay means responsive to the wait means for opening a listen window in the local coder to the remote coder as the local coder advances from the normal mode of operation to the wait mode of operation;
listen means for detecting the in-coming wait signal from the remote coder during the wait mode to determine if the remote coder has advanced to the wait mode of operation;
send means responsive to the listen means for opening a send window, and for sending an out-going wait signal to the remote coder indicating that the local coder has advanced to the wait mode of operation;
lockout means responsive to the listen means and to the send means for advancing the local coder from the wait mode of operation to a code mode of operation during which the local coder and the remote coder are enabled to encode out-going communications and to decode in-coming communications, and for locking out any extension coders from the encoding and decoding;
code means responsive to the lockout means for the encoding out-going communications from the local coder to the remote coder during the code mode, and for decoding in-coming communications to the local coder from the remote coder during the code mode.
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Accused Products
Abstract
Remote telephone coder 10R and local telephone coder 10L provide coding and decoding for voice communication between remote telephone set 11R and local telephone set 11L through telephone line 12. An eavesdropper listening in on a listening device such as remote extension telephone 14R or local extension telephone 14L hears normal "in-the-clear" conversation (uncoded transmissions) when both of the telephone coders are in the normal mode. However, when both of telephone coders 10R and 10L are in the code mode, the extension eavesdropper using an extension telephone or other unauthorized listening device 14 (shown in phantom) hears only coded transmissions. Further, a remote eavesdropper on remote extension telephone set (main portion 17M with hand portion 17H) employing remote extension coder 16R is also excluded from the coded transmissions between remote telephone coder 10R and local telephone coder 10L.
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Citations
33 Claims
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1. A local communication coder for linking between a local telephone and a telecommunication system, and responsive to an in-coming wait signal from a cooperating remote communication coder linked to the telecommunication system, for enabling the local coder and the remote coder to encode and decode communications, and for locking out any cooperating extension communication coders linked to the telecommunication system from encoding and decoding communications, the local coder comprising:
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wait means for advancing the local coder from a normal mode of operation during which out-going communications from the local coder are not encoded and in-coming communications to the local coder are not decoded, to a wait mode of operation during which the local coder listens for the wait signal from the remote coder; listen delay means responsive to the wait means for opening a listen window in the local coder to the remote coder as the local coder advances from the normal mode of operation to the wait mode of operation; listen means for detecting the in-coming wait signal from the remote coder during the wait mode to determine if the remote coder has advanced to the wait mode of operation; send means responsive to the listen means for opening a send window, and for sending an out-going wait signal to the remote coder indicating that the local coder has advanced to the wait mode of operation; lockout means responsive to the listen means and to the send means for advancing the local coder from the wait mode of operation to a code mode of operation during which the local coder and the remote coder are enabled to encode out-going communications and to decode in-coming communications, and for locking out any extension coders from the encoding and decoding; code means responsive to the lockout means for the encoding out-going communications from the local coder to the remote coder during the code mode, and for decoding in-coming communications to the local coder from the remote coder during the code mode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A local cordless coder telephone comprising:
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base unit for linking to a telecommunication system for communication with the remote coder, and having a local transmitter-receiver; cordless unit having a local transmitter-receiver in communication with the base transmitter-receiver, a microphone-speaker for user communications, and a local coder coupled between the cordless transmitter-receiver and the microphone-speaker for encoding and decoding the user communications; wait means within the local coder for advancing the local coder from a normal mode of operation during which communications transmitted from the cordless unit to the base unit are not encoded and communications received by the cordless unit from the base unit are not decoded, to a wait mode of operation during which the local coder listens for the in-coming wait signal from a cooperating remote coder also linked to the telecommunication system; listen delay means within the local coder responsive to the wait means for opening a listen window as the local coder advances from the normal mode to the wait mode; listen means within the local coder for detecting the in-coming wait signal from the remote coder during the wait mode indicating that the remote coder has advanced to the wait mode; send means within the local coder responsive to the listen means for opening a send window, and for sending an out-going wait signal to the remote coder indicating that the local coder has advanced to the wait mode; lockout means within the local coder responsive to the listen means and to the send means for advancing the local coder from the wait mode to a code mode during which the local coder and the remote coder are enabled to encode transmitted communications and to decode received communications, and during which any extension coders linked to the telecommunication system are locked out from the encoding and decoding; and code means within the local coder responsive to the lockout means for encoding communications transmitted from the cordless unit to the base unit during the code mode, and for decoding communications received by the cordless unit from the base unit during the code mode.
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31. A coder method of enabling encoding and decoding communications between a local telephone and a remote telephone and locking out any extension telephones, comprising:
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providing a local coder in a normal mode of operation during which out-going communications from the local coder are not encoded and in-coming communications to the local coder are not decoded; advancing the local coder from the normal mode of operation to a wait mode of operation during which the local coder listens for an in-coming wait signal from the remote coder; opening a send window in the local coder to the remote coder during the wait mode; sending an out-going wait signal to the remote coder during the send window indicating that the local coder has advanced to the wait mode; closing the send window during the wait mode; advancing the local coder from the wait mode of operation to a code mode of operation during which the local coder and the remote coder are enabled to encode out-going communications and to decode in-coming communications, and during which any extension coders are prevented from the encoding and decoding; encoding out-going communications from the local coder to the remote coder during the code mode; and decoding in-coming communications to the local coder from the remote coder during the code mode. - View Dependent Claims (32, 33)
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Specification