Telephone set identification system

Claim 2

A party telephone identification system comprising: a central office including a high potential source having a value substantially greater than the central office battery potential; a multiparty subscriber''s line connected into said central office; a plurality of telephone sets connected to said line, each said set having on hook and off hook conditions; circuit means in said central office for connecting said high potential source to said line, and electrical signal generating means connected in each of said sets, so that when a set is in the off hook condition and said central office potential source is connected to said line, said signal generating means generates and transmits an identification oscillatory signal unique to said off hook set to the central office.

Claim 3

A party identification system as set forth in claim 1 wherein: said electrical signal generating means includes at least one inductance, resistance, capacitance tuned circuit, the arrangement being such that said tuned circuit selects the resonant frequency when said high potential signal is connected to said telephone line.

Claim 4

In a telephone system, a telephone set, a line connecting said telephone set to a central office, circuit means in said central office for applying to said telephone line a D.C. potential which is substantially greater than the central office battery potential, and means in said telephone set responsive to said D.C. potential when the telephone set is in the off hook condition for transmitting an oscillatory identification signal to said central office.

Claim 5

In a telephone system, a telephone set, a line connecting said telephone set to a central office, circuit means in said central office for applying to said telephone line a D.C. potential which is substantially greater than the central office battery potential, and means in said telephone set responsive to said D.C. potential when the telephone set is in the off hook condition for transmitting an oscillatory identification signal to said central office.

Claim 6

A telephone system as defined in claim 3 wherein said means in said telephone set includes an oscillator circuit connected to the telephone line via the telephone set hookswitch contacts and said oscillator circuit oscillates in response to said D.C. potential.

Claim 7

A telephone system as defined in claim 4 wherein said means in said telephone set includes a multifrequency oscillator circuit coupled to a pushbutton dial to provide multifrequency dial signals and circuit means coupled to said oscillator circuit for rendering the oscillator responsive to said D.C. potential.

Claim 8

A telephone system as defined in claim 4 wherein said oscillator circuit generates a plurality of frequencies during the presence of said D.C. potential.

Claim 9

In a telephone subset including a multifrequency oscillator circuit having a pair of tuned inductance-capacitance circuits with a plurality of switches for connecting the capacitance to various portions of the inductance to control the frequency of oscillation, switching means for connecting the oscillator circuit to the telephone line via the telephone hookswitch contacts, and a pushbutton dial connected to the switching means and the plurality of switches for connecting the oscillator circuit to said hookswitch contacts and closing a switch in each of the tuned circuits each time a pushbutton is depressed, the improvement comprising: circuit means connected to shunt one of the plurality of switches in at least one of said tuned circuits, and resistor means connected across said switching means so that said oscillator circuit is enabled to oscillate at the frequency corresponding to the tuned circuit having the shunt circuit means when the telephone hookswitch is in the off hook condition and a high potential is applied across the telephone line that is substantially greater than 48 volts.

Claim 10

In a telephone subset including a multifrequency oscillator circuit having a pair of tuned inductance-capacitance circuits with a plurality of switches for connecting the capacitance to various portions of the inductance to control the frequency of oscillation, switching means for connecting the oscillator circuit to the telephone line via the telephone hookswitch contacts, and a pushbutton dial connected to the switching means and the plurality of switches for connecting the oscillator circuit to said hookswitch contacts and closing a switch in each of the tuned circuits each time a pushbutton is depressed, the improvement comprising: circuit means connected to shunt one of the plurality of switches in at least one of said tuned circuits, and resistor means connected across said switching means so that said oscillator circuit is enabled to oscillate at the frequency corresponding to the tuned circuit having the shunt circuit means when the telephone hookswitch is in the off hook condition and a high potential is applied across the telephone line that is substantially greater than 48 volts.

Claim 11

In a telephone subset as defined in claim 7 wherein: separate circuit means is connected to shunt one of the plurality of switches in each of said tuned circuits so that the oscillator circuit when energized by said high potential generates the frequencies corresponding to the dial frequencies of the two switches shunted.

Claim 12

In a telephone subset as defined in claim 8 wherein: said separate circuit means comprises a series resistor and capacitor circuit.

Claim 13

In a telephone subset as defined in claim 8 wherein: both of said separate circuit means comprises a normally closed switch that is coupled to said pushbutton dial to be opened each time a pushbutton is depressed, and wherein the normally closed switches open before any of said plurality of switches close.

Claim 14

In a rotary dial type telephone, the improvement comprising: a pair of terminals for connection to a telephone exchange; a hookswitch having off hook and on hook conditions connected to said pair of terminals; an oscillator circuit; a tuned circuit including an inductor and a capacitor, inductively coupled to said oscillator circuit for determining the frequency of oscillation, and resistive means coupling said oscillator circuit to said hookswitch so that when said hookswitch is on the off hook condition and a potential substantially greater than 48 volts is applied across said pair of terminals, said oscillator circuit is energized by said potential to break into oscillation and apply the oscillation signals to said pair of terminals.

Claim 15

In a rotary dial type telephone, the improvement comprising: a pair of terminals for connection to a telephone exchange; a hookswitch having off hook and on hook conditions connected to said pair of terminals; an oscillator circuit; a tuned circuit including an inductor and a capacitor, inductively coupled to said oscillator circuit for determining the frequency of oscillation, and resistive means coupling said oscillator circuit to said hookswitch so that when said hookswitch is on the off hook condition and a potential substantially greater than 48 volts is applied across said pair of terminals, said oscillator circuit is energized by said potential to break into oscillation and apply the oscillation signals to said pair of terminals.