Communication call holding circuit

Claim 2

A call holding circuit comprising means applying a hold condition for a call on a communication line, and means subsequently responsive solely to an on-hook and then an off-hook signal received from said line for automatically controlling said applying means to withdraw said call hold condition.

Claim 3

A telephone call holding circuit operating solely on power supplied over a telephone line and comprising means activatable under control of said supplied power for applying a hold condition on said line, means effective during a call on said line for activating said applying means to apply said hold condition on said line for said call, and means subsequently responsive to a telephone on-hook signal followed by a telephone off-hook signal on said line for automatically deactivating said applying means to withdraw said hold condition from said line.

Claim 4

A telephone call holding circuit operating solely on power supplied over a telephone line and comprising means activatable under control of said supplied power for applying a hold condition on said line, means effective during a call on said line for activating said applying means to apply said hold condition on said line for said call, and means subsequently responsive to a telephone on-hook signal followed by a telephone off-hook signal on said line for automatically deactivating said applying means to withdraw said hold condition from said line.

Claim 5

A telephone call holding circuit according to claim 2, wherein said applying means includes a bistable switch device, said activating means includes a pushbutton momentarily actuated for activating said switch device for applying said holding condition, and wherein said deactivating means includes a capacitor controlled by said on-hook and off-hook signals for automatically deactivating said switch device.

Claim 6

A telephone call holding circuit operating solely on power supplied over a telephone line shared by a plurality of telephones each of which is equipped with a pushbutton switch and said circuit comprising holding means connected to said line and responsive during a call to an actuation of one of said pushbutton switches for applying a hold condition to said telephone line, and means subsequently responsive solely to a prescribed sequence of on-hook and off-hook signals on said line under control of said telephones for automatically controlling said holding means to remove said hold condition from said line.

Claim 7

A telephone call holding circuit operating solely on power supplied over a telephone line shared by a plurality of telephones each of which is equipped with a pushbutton switch and said circuit comprising holding means connected to said line and responsive during a call to an actuation of one of said pushbutton switches for applying a hold condition to said telephone line, and means subsequently responsive solely to a prescribed sequence of on-hook and off-hook signals on said line under control of said telephones for automatically controlling said holding means to remove said hold condition from said line.

Claim 8

In combination, means selectively activated for holding communication connections on a communication line, means responsive to a subsequent receipt of a disconnect signal on said line for storing a predetermined electrical signal during said holding of said connections, and said holding means being automatically deactivated by said electrical signal upon a subsequent receipt of an answer signal on said line for withdrawing said holding of connections.

Claim 9

In combination, means selectively activated for holding communication connections on a communication line, means responsive to a subsequent receipt of a disconnect signal on said line for storing a predetermined electrical signal during said holding of said connections, and said holding means being automatically deactivated by said electrical signal upon a subsequent receipt of an answer signal on said line for withdrawing said holding of connections.

Claim 10

The combination in accordance with claim 5 wherein said storing means includes a capacitor being charged in response to said disconnect signal on said line, and said capacitor being further responsive to said answer signal on said line for discharging to effect a deactivating of said holding means to withdraw said holding of connections.

Claim 11

The combination in accordance with claim 6 wherein said holding means comprises a transistor arrangement connected to said line, further comprising a switching device selectively actuated for activating said transistor arrangement for applying a hold condition to said line, said activated transistor arrangement being effective for charging said capacitor in response to said disconnect signal, and said charged capacitor being responsive to said answer signal on said line for discharging to deactivate said transistor arrangement to withdraw said holding of connections.

Claim 12

A holding circuit for a communication line comprising a transistor arrangement selectively activated for holding a call on said line, capacitoR means charged through said arrangement in response to a call disconnect signal on said line, and said capacitor means being responsive to a subsequent call answer signal for discharging to deactivate said transistor arrangement for automatically withdrawing said call holding on said line.

Claim 13

A holding circuit for a communication line comprising a transistor arrangement selectively activated for holding a call on said line, capacitoR means charged through said arrangement in response to a call disconnect signal on said line, and said capacitor means being responsive to a subsequent call answer signal for discharging to deactivate said transistor arrangement for automatically withdrawing said call holding on said line.

Claim 14

A holding circuit in accordance with claim 8 wherein said transistor arrangement includes a PNPN device having gate, cathode and anode electrodes, and further comprising switch means selectively actuated for applying a gating signal to said gate electrode for activating said PNPN device to a low resistance state between said anode and cathode electrodes for holding a call on said line.

Claim 15

A holding circuit in accordance with claim 9 wherein said capacitor means charges through said cathode and anode electrodes of said PNPN device in response to said call disconnect signal on said line, and said capacitor means is connected to said anode electrode for discharging to deactivate said PNPN device to a high resistance state between said anode and cathode electrodes for automatically withdrawing said call holding on said line.

Claim 16

A holding circuit in accordance with claim 10 further comprising a resistor-capacitor network serially connected with said switch means and said anode electrode for generating said gating signal upon an actuation of said switch means, and a resistor connected in parallel with said capacitor means and to said anode electrode, and wherein said activation of said PNPN device to said low resistance state causes said capacitor means to charge to a first voltage developed across said resistor.

Claim 17

A holding circuit in accordance with claim 11 wherein said capacitor means increasingly charges to a second voltage developed across said resistor in response to said call disconnect signal on said line, and said capacitor means discharging from said second voltage for producing a signal at said anode electrode which deactivates said PNPN device to said high resistance state for automatically withdrawing said call holding on said line.

Claim 18

An electronic call holding circuit comprising a PNPN switch selectively activated to a low resistance state for providing a hold condition on a communication line, a capacitor, and subset apparatus connected to said line for controlling a charging of said capacitor through said activated switch upon a generation of a call disconnect signal by said apparatus, and said capacitor being subsequently discharged in response to a call answer signal on said line under control of said apparatus for automatically deactivating said switch to a high resistance state for withdrawing said hold condition on said line.

Claim 19

An electronic call holding circuit comprising a PNPN switch selectively activated to a low resistance state for providing a hold condition on a communication line, a capacitor, and subset apparatus connected to said line for controlling a charging of said capacitor through said activated switch upon a generation of a call disconnect signal by said apparatus, and said capacitor being subsequently discharged in response to a call answer signal on said line under control of said apparatus for automatically deactivating said switch to a high resistance state for withdrawing said hold condition on said line.

Claim 20

In a telephone system having a telephone line including tip and ring conductors, a first subset connected to said conductors and being operative for call communication over said line, a PNPN switch connected between said conductors, means including a pushbutton momentarily actuable for controlling the switching of said switch to a low impedance state between said conductors to place a hold condition on said line, said first subset being controllable for discontinuing call communication over said line while said switch holds said call on said line, a second subset subsequently connected to said conductors for call communication, and control means automatically responsive to said connection of said second subset to said conductors for switching said switch to a high impedance state to remove said hold condition on said line.

Claim 21

In a telephone system having a telephone line including tip and ring conductors, a first subset connected to said conductors and being operative for call communication over said line, a PNPN switch connected between said conductors, means including a pushbutton momentarily actuable for controlling the switching of said switch to a low impedance state between said conductors to place a hold condition on said line, said first subset being controllable for discontinuing call communication over said line while said switch holds said call on said line, a second subset subsequently connected to said conductors for call communication, and control means automatically responsive to said connection of said second subset to said conductors for switching said switch to a high impedance state to remove said hold condition on said line.

Claim 22

In a telephone system according to claim 14, the combination wherein said first subset discontinuing of call communication effects an application of an on-hook signal to said conductors, said control means includes a capacitor charged through said low impedance of said PNPN switch in response to said on-hook signal, said second subset connection to said conductors effects an applicatiOn of an off-hook signal to said conductors, and said capacitor being responsive to said off-hook signal for discharging to effect said switching of said PNPN switch to a high impedance state to remove said hold condition on said line.

Claim 23

In a telephone system according to claim 15, the combination wherein said means including said pushbutton comprises an electrical network including said control means capacitor to generate an electrical signal for switching said PNPN switch into said low impedance state between said conductors to place a hold condition on said line.

Claim 24

In a telephone system according to claim 16, the combination wherein said PNPN switch includes cathode, gate and anode electrodes, said cathode being connected to a first one of said line conductors, further comprising a first resistor connected in series with said anode and a second one of said line conductors, said control means capacitor being connected in parallel with said first resistor, and said electrical network includes a resistor-capacitor arrangement serially connected with said pushbutton between said anode and gate electrodes.

Claim 25

In a telephone system according to claim 17, the combination further comprising electrical voltage for operating said PNPN switch supplied from said line conductors, a polarity guard diode arrangement connected between said cathode and said parallel connected control means capacitor and said first resistor, and wherein said pushbutton is momentarily actuatable to generate said electrical signal at said gate electrode for switching said PNPN switch into a low impedance state between said cathode and anode electrodes, whereby an electrical holding condition is applied across said line conductors through said diode arrangement, said cathode and anode electrodes, and said first resistor.

Claim 26

In a telephone system according to claim 18, the combination wherein said control means capacitor charges to a voltage developed across said first resistor during said holding condition on said line, said on-hook signal effects an increase in said electrical voltage developed across said first resistor, and said control means capacitor automatically charges to said increased voltage through said cathode and anode electrodes of said PNPN switch.

Claim 27

In a telephone system according to claim 19, the combination wherein said off-hook signal effects a decrease in said electrical voltage developed across said first resistor, and said control means capacitor automatically discharges in response to said voltage decrease for effecting a switching of said PNPN switch to a high impedance state to remove said hold condition on said line.

Claim 28

A telephone line holding circuit for a telephone line having multiple station sets connected thereto, said call holding circuit comprising electronic switch means, means for connecting said switch means to the telephone line whereby direct current from a central office can flow through said switch means, and means for applying a transient voltage from the central office to said switch means to place said switch means in a low impedance state, whereby the connection from the central office on the telephone line is held by said switch means.

Claim 29

A telephone line holding circuit for a telephone line having multiple station sets connected thereto, said call holding circuit comprising electronic switch means, means for connecting said switch means to the telephone line whereby direct current from a central office can flow through said switch means, and means for applying a transient voltage from the central office to said switch means to place said switch means in a low impedance state, whereby the connection from the central office on the telephone line is held by said switch means.

Claim 30

A telephone line holding circuit in accordance with claim 21 further comprising a capacitor connected to said connecting means to be charged to a first potential on said switch means being placed in said low impedance state, to be charged to a higher potential when the stations for that telephone line are all on-hook, and to be discharged to a lower potential when a station set for that telephone line goes off-hook, thereby to return said switch means to a high impedance state.

Claim 31

A telephone line holding circuit in accordance with claim 22 wherein said switch means comprises transistor means, said connecting means includes a resistor, said applying means includes means defining a voltage divider, and Said capacitor is connected across said resistor.