Telephone station set interface circuit

Claim 2

An interface circuit for use between a telephone switching system and a nonkey telephone station set wherein said telephone switching system transmits control signals to and receives status signals from each telephone station set associated with said telephone switching system over a data link independent of a speech path; wherein said interface circuit comprises: means for terminating said data link independent of said speech path connected to said nonkey telephone station set; means for receiving said control signals from said telephone switching system over said data link; and means controlled by said nonkey telephone station set for transmitting said control signals back over said data link to said telephone switching system to indicate the status of said nonkey telephone station set.

Claim 3

The invention of claim 1 wherein said means controlled by said nonkey telephone station set comprises: means controlled by the off-hook state of said nonkey telephone station set and responsive to the receipt of said control signals from said telephone switching system over said data link for retransmitting said control signals back to said telephone switching system over said data link to indicate the off-hook status of said nonkey telephone station set, and means controlled by the on-hook state of said nonkey telephone station set and responsive to the receipt of said control signals from said telephone switching system over said data link for blocking the retransmission of said control signals back to said telephone switching system over said data link to indicate the on-hook status of said nonkey telephone station set.

Claim 4

The invention of claim 2 wherein: said data link comprises a data transmit pair for carrying said control signals from said interface circuit to said telephone switching system to indicate the busy state of said nonkey telephone station set, a data receive pair for carrying said control signals from said telephone switching system to said interface circuit; and said means controlled by the off-hook state of said nonkey telephone station set comprises a relay and a transformer for connecting said data transmit pair to said data receive pair.

Claim 5

The invention of claim 3 wherein said means controlled by the on-hook state of said nonkey telephone station set comprises contacts of said relay which open in response to the on-hook condition of said nonkey telephone station set and which disjoin said data transmit pair from said data receive pair.

Claim 6

The invention of claim 1 wherein said control signals received by said interface circuit from said telephone switching system include ringing control information, wherein said interface circuit additionally comprises: means for detecting said ringing control information; and means for generating an audible tone signal in response to the detection of said ringing control information.

Claim 7

The invention set forth in claim 5 wherein said control signals include signals having a first duration and a second duration longer than said first duration wherein said ringing control information signals are of said second duration; and said detecting means includes timing means responsive to the receipt of said control signals from said telephone switching system over said data link having said second duration for enabling said generating means.

Claim 8

The invention of claim 6 wherein said timing means is responsive solely to the duration of said control signals.

Claim 9

The invention of claim 6 wherein said generating means is powered exclusively from said data link.

Claim 10

An interface circuit for use in an electronic telephone switching system having at least one conventional nonkey telephone station set and a plurality of electronic key telephone station sets, wherein said electronic telephone switching system transmits control data signals to and receives call data signals from each said electronic key telephone station set over a corresponding data link independent of a speech path; wherein said interface circuit is associated with each said conventional nonkey telephone station set and comprises: means for providing a termination for said data link independent of said speech path connected to said conventional nonkey telephone station set; means for receiving said control data signals from said electronic telephone switching system over said data link independent of said speech path; and means for transmitting said received control data signals over said data link to said electronic telephone switching system to indicate the status of said nonkey telephone station set.

Claim 11

An interface circuit for use in an electronic telephone switching system having at least one conventional nonkey telephone station set and a plurality of electronic key telephone station sets, wherein said electronic telephone switching system transmits control data signals to and receives call data signals from each said electronic key telephone station set over a corresponding data link independent of a speech path; wherein said interface circuit is associated with each said conventional nonkey telephone station set and comprises: means for providing a termination for said data link independent of said speech path connected to said conventional nonkey telephone station set; means for receiving said control data signals from said electronic telephone switching system over said data link independent of said speech path; and means for transmitting said received control data signals over said data link to said electronic telephone switching system to indicate the status of said nonkey telephone station set.

Claim 12

The invention of claim 9 wherein each said data link comprises a data transmit pair for carrying said call data signals from said electronic key telephone station set to said electronic telephone switching system, a data receive pair for carrying said control data signals from said electronic telephone switching system to said electronic key telephone station set; wherein said interface circuit transmitting means comprises: means responsive to the receipt of said control data signals from said electronic telephone switching system over said data receive pair for retransmitting said control data signals to said electronic telephone switching system over said data transmit pair when the conventional nonkey telephone station set associated with said interface circuit is off-hook; and means responsive to the receipt of said control data signals from said electronic telephone switching system over said data receive pair for blocking the retransmission of said control data signals to said electronic telephone switching system over said data transmit pair when the conventional nonkey telephone station set associated with said interface circuit is on-hook.

Claim 13

The invention of claim 10 wherein: said retransmitting means comprises a transformer for connecting said data transmit pair to said data receive pair; and said blocking means comprises contacts which respond to the switchhook condition of said nonkey telephone station set associated with said interface circuit and which disjoin said data transmit pair from said data receive pair.

Claim 14

The invention set forth in claim 11 wherein said control data signals include signals having a first bit length; wherein said control data signals additionally include ringing control information signals having a second bit length longer than said first bit length; wherein said interface circuit includes: audio signal generating means; and means for detecting said ringing control information wherein said detecting means includes timing means responsive to the receipt of said control data signal from said electronic telephone switching system over said data receive pair having said second bit length for enabling said signal generating means.

Claim 15

The invention of claim 12 wherein said interface circuit further includes: power separation means for exclusively powering said interface circuit from power supplied by said electronic telephone switching system over said data link.

Claim 16

In an electronic key telephone system having at least one conventional nonkey telephone station set and a plurality of electronic key telephone station sets, wherein said electronic key telephone station set transmits data to and receives data from said electronic key telephone system over a data link independent of a speech path; an interface circuit associated with each said conventional nonkey telephone station set for providing a termination for said data link independent of said speech path connected to said conventional nonkey telephone station set, wherein said interface circuit comprises: means responsive to the receipt of said data from said electronic key telephone system over said data link for retransmitting the received data to said electronic key telephone system over said data link when the conventional nonkey telephone station set associated with said interface circuit is off-hook; means responsive to the receipt of said data from said electronic key telephone system over said data link for blocking the return of said received data to said electronic key telephone system over said data link when the conventional nonkey telephone station set associated with said interface circuits is on-hook; detecting means responsive to the receipt of data containing ringing control information from said electronic key telephone system over said data link for generating an output signal; and generating means responsive to said output signal for generating an audible tone at said conventional nonkey telephone station set.

Claim 17

In an electronic key telephone system having at least one conventional nonkey telephone station set and a plurality of electronic key telephone station sets, wherein said electronic key telephone station set transmits data to and receives data from said electronic key telephone system over a data link independent of a speech path; an interface circuit associated with each said conventional nonkey telephone station set for providing a termination for said data link independent of said speech path connected to said conventional nonkey telephone station set, wherein said interface circuit comprises: means responsive to the receipt of said data from said electronic key telephone system over said data link for retransmitting the received data to said electronic key telephone system over said data link when the conventional nonkey telephone station set associated with said interface circuit is off-hook; means responsive to the receipt of said data from said electronic key telephone system over said data link for blocking the return of said received data to said electronic key telephone system over said data link when the conventional nonkey telephone station set associated with said interface circuits is on-hook; detecting means responsive to the receipt of data containing ringing control information from said electronic key telephone system over said data link for generating an output signal; and generating means responsive to said output signal for generating an audible tone at said conventional nonkey telephone station set.

Claim 18

The invention of claim 14 wherein said data include signals having a first bit length; wherein said data additionally include ringing control information signals having a second bit length longer than said first bit length; and said detecting means include timing means responsive to the receipt of said data from said electronic telephone switching system over said data link having said second bit length for enabling said generating means.

Claim 19

The invention of claim 15 wherein said interface circuit further includes: power separation means for exclusively powering said interface circuit from power supplied by said electronic telephone switching system over said data link.