Artificial line busy circuit

Claim 2

A line busy circuit for a communication line comprising means operated in response to an incoming call for supplying a busy signal to said line for making said line appear busy to said call, timer means responsive to the operation of said supplying means for defining a timed interval, and means activated by said timer means for automatically controlling said supplying means upon an expiration of said timed interval to withdraw said busy signal from said line.

Claim 3

A line busy circuit in accordance with claim 1 wherein said supplying means includes means operated in response to incoming call ringing for connecting a busy tone to said line.

Claim 4

A line busy circuit in accordance with claim 2 wherein said supplying means further includes means controlled by said connecting means in response to said incoming call ringing for providing an off-hook signal on said line for tripping said ringing current and for holding said call on said line.

Claim 5

A line busy circuit in accordance with claim 3 wherein said off-hook signal providing means includes a resistor, and said connecting means includes a relay operated in response to said incoming call ringing current for connecting said resistor across said line to provide said off-hook signal for said timed interval.

Claim 6

A line busy circuit in accordance with claim 1 wherein said timer means comprises a first relay responsive to an operation of said supplying means for defining an initial portion of said timed interval, and a second relay operable for defining a last portion of Said timed interval.

Claim 7

A line busy circuit in accordance with claim 5 wherein said timer means further includes another relay activated by said first relay at the expiration of said initial portion of said timing interval for causing an operation of said second relay for defining said last portion of said time interval.

Claim 8

A line busy circuit in accordance with claim 6 further comprising signal means operable for providing a humanly detectable signal of the receipt of said call, and means responsive to said operation of said supplying means for operating said signal means, wherein said other relay includes means actuated upon the operation of said other relay for releasing said first relay and said signal means during the definition of said last portion of said timed interval.

Claim 9

A line busy circuit in accordance with claim 7 wherein said second relay includes means for releasing said supplying means upon an expiration of said timed interval to withdraw said busy signal from said line.

Claim 10

A line busy circuit in accordance with claim 5 wherein said supplying means includes an electrical bridge network comprising a busy tone source and an off-hook signal device, a ring detector relay responsive to incoming call ringing current for connecting both said tone source and said off-hook device to said line to make said line appear busy to said incoming call, and wherein said first timer relay is responsive to an operation of said detector relay for defining said initial portion of said timed interval, said second timer relay including means effective for holding said detector relay operated until after an expiration of said last portion of said timed interval, and said second relay means being operated at the expiration of said timed interval for releasing said detector relay to disconnect said tone source and off-hook device from said line.

Claim 11

In a telephone system having a telephone line, an electrical line termination device, means operated in response to a receipt of an incoming call on said line for connecting said termination device to said line, and means subsequently responsive to a termination of said call for effecting a busy condition of said line under control of said termination device connected thereto, the improvement comprising timer means responsive to said operation of said connecting means for defining a timed interval, and apparatus activated by said timer means at the expiration of said interval for controlling said connecting means to disconnect said termination device from said line to control a removal of said line busy condition.

Claim 12

In a telephone system having a telephone line, an electrical line termination device, means operated in response to a receipt of an incoming call on said line for connecting said termination device to said line, and means subsequently responsive to a termination of said call for effecting a busy condition of said line under control of said termination device connected thereto, the improvement comprising timer means responsive to said operation of said connecting means for defining a timed interval, and apparatus activated by said timer means at the expiration of said interval for controlling said connecting means to disconnect said termination device from said line to control a removal of said line busy condition.