EP0196834A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Security arrangement for cordless telephone system
Assignee: AT&T Inc
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Filing: 1986-03-20
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Granted: —
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Expires: 2006-03-20
Abstract
Abstract A security system for cordless telephones prevents unauthorized telephone calls over telephone lines. The system includes a base unit 10 and a cordless handset unit 50 which must share common information for proper operation. To prevent an unauthorized user in possession of a handset unit from easily matching a security code stored in the base unit and thereby obtain dial tone thereform, the security code in the base unit is transferred to the handset unit while the handset unit is in a mating cradle in the base unit. Transfer circuits 12, 13, 14 in the base unit and the handset unit 51, 53 respectively transmit and receive the security code and also an operating frequency channel over a direct-current charging path provided for charging of a battery in the handset unit whenever the handset unit is returned to the cradle.
Inventors
- 👤 Ronald Edward Anglikowski
- 👤 Nissin Habib
- 👤 Arden Bernard Wright
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 09:44
CPC Classifications
H; H04; H04M; H04M11/00; H04M1/00; H04M1/72; H04M1/725; H04M1/72502; H04M1/72505; H04M1/72511; H04M1/727
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
266 words
A security arrangement for preventing unauthorized placing of telephone calls in a cordless telephone system over telephone lines associated with the system, the system including a base unit for connection to the telephone lines and for transmitting to and receiving signals from a remote unit associated with the base unit, the remote unit also transmitting to and receiving signals from the base unit, and the base unit being adapted for activation by the remote unit to cause dial tone to be transmitted to the remote unit for placing a telephone call therefrom, the security arrangement, adapted to store a predetermined signal code in the base unit for preventing the base unit from responding to an unauthorized remote unit, CHARACTERIZED BY means (13, 14, 51, 53) located in the base unit for transmitting and in the associated remote unit 50 for receiving the predetermined signal code over an electrical path established when the remote unit is brought in electrical contact with the base unit, the remote unit storing the signal code for transmission back to the base unit when located remote from the base unit and requesting dial tone therefrom; comparison means 13 in the base unit for comparing the predetermined signal code stored therein with the signal code received from a remote unit requesting dial tone; and activation means 13 in the base unit responsive to the comparison means, the activation means causing dial tone to be transmitted to the remote unit requesting dial tone when the signal code received from the remote unit is equivalent to the predetermined signal code stored in the base unit.
Claim 2
Dependent Claim
266 words
A security arrangement for preventing unauthorized placing of telephone calls in a cordless telephone system over telephone lines associated with the system, the system including a base unit for connection to the telephone lines and for transmitting to and receiving signals from a remote unit associated with the base unit, the remote unit also transmitting to and receiving signals from the base unit, and the base unit being adapted for activation by the remote unit to cause dial tone to be transmitted to the remote unit for placing a telephone call therefrom, the security arrangement, adapted to store a predetermined signal code in the base unit for preventing the base unit from responding to an unauthorized remote unit, CHARACTERIZED BY means (13, 14, 51, 53) located in the base unit for transmitting and in the associated remote unit 50 for receiving the predetermined signal code over an electrical path established when the remote unit is brought in electrical contact with the base unit, the remote unit storing the signal code for transmission back to the base unit when located remote from the base unit and requesting dial tone therefrom; comparison means 13 in the base unit for comparing the predetermined signal code stored therein with the signal code received from a remote unit requesting dial tone; and activation means 13 in the base unit responsive to the comparison means, the activation means causing dial tone to be transmitted to the remote unit requesting dial tone when the signal code received from the remote unit is equivalent to the predetermined signal code stored in the base unit.
Claim 3
Dependent Claim
35 words
The security arrangement of claim 1 CHARACTERIZED IN THAT the associated remote unit is brought into electrical contact with the base unit by placing the remote unit in a mating cradle in the base unit.
Claim 4
Dependent Claim
35 words
The security arrangement of claim 1 CHARACTERIZED IN THAT a different predetermined signal code is stored in the base unit each time the associated remote unit is brought into electrical contact with the base unit.
Claim 5
Dependent Claim
58 words
The security arrangement of claim 3 CHARACTERIZED IN THAT the base unit further comprises a random number generator for generating a random number for use as the. different predetermined signal code, the random number being stored in memory in a code select circuit 12 for comparison with a signal code received from the remote unit requesting dial tone.
Claim 6
Dependent Claim
72 words
The security arrangement of claim 1 CHARACTERIZED IN THAT the means for transmitting and receiving the predetermined signal code from the base unit to the associated remote unit comprises the electrical contact made by a direct current charging path 141, 142, 511, 512 established when the remote unit is placed in a mating cradle in the base unit, the charging path being used for charging a battery 54 in the remote unit.
Claim 7
Dependent Claim
78 words
The security arrangement of claim 5 CHARACTERIZED IN THAT the means located in the base unit for transmitting the signal code further comprises a first transistor 145 for providing a signal indication to a control circuit in the base unit when the associated remote unit is brought into electrical contact with the base unit, the first transistor providing an activation signal for initiating the transmitting of the predetermined signal code from the control circuit to the remote unit.
Claim 8
Dependent Claim
73 words
The security arrangement of claim 6 CHARACTERIZED IN THAT the means located in the base unit for transmitting the signal code further comprises a second transistor 517 coupled to the control circuit and responsive thereto for transmitting the signal code over the electrical contact made by the direct current charging path, the second transistor generating a serial data stream across the charging path by being pulsed off and on by the control circuit.
Claim 9
Dependent Claim
95 words
The security arrangement of claim 5 CHARACTERIZED IN THAT the means located in the associated remote unit for receiving the signal code further comprises a first transistor 517 for providing a signal indication to a control circuit in the remote unit when the remote unit is brought into electrical contact with the base unit, the first transistor providing an activation signal for switching the remote unit from a talk to a standby mode wherein the transmission of the predetermined signal code from the base unit to the control circuit in the remote unit is performed.
Claim 10
Dependent Claim
98 words
The security arrangement of claim 8 CHARACTERIZED IN THAT- the means located in the associated remote unit for transmitting the signal code further comprises means for transmitting an acknowledge signal back to the base unit for indicating receipt of the signal code, the acknowledge signal means comprising a second transistor 519 coupled to the control circuit and responsive thereto for transmitting the signal code over the electrical contact made by the direct current charging path, and the second transistor generating a serial data stream across the charging path by being pulsed off and on by the control circuit.
Claim 11
Dependent Claim
45 words
The security arrangement of claim 1 CHARACTERIZED IN THAT the signal code further includes a security code for establishing communications between the base unit and the associated remote unit, and frequency channel information for setting the transmitting and receiving signal frequency of the remote unit.
Claim 12
Dependent Claim
46 words
The security arrangement of claim 10 CHARACTERIZED IN THAT the remote unit, upon receipt of the signal code from the base unit, sets its transmitting and receiving signal frequency and stores the security code for transmission back to the base unit when requesting dial tone therefrom.
Claim 13
Independent Claim
238 words
A method of preventing unauthorized placing of telephone calls in a cordless telephone system over telephone lines associated with the system, the system including a base unit for connection to the telephone lines and for transmitting to and receiving signals from a remote unit associated with the base unit, the remote unit also transmitting to and receiving signals from the base unit, and the base unit being activatable by the remote unit to cause dial tone to be transmitted to the remote unit for placing a telephone call therefrom, the method CHARACTERIZED BY storing a predetermined signal code in the base unit for preventing the base unit from responding to an unauthorized remote unit; transmitting the predetermined signal code from the base unit and receiving the predetermined signal code in the associated remote unit over an electrical path established when the remote unit is brought in electrical contact with the base unit; storing the signal code by the remote unit for transmission back to the base unit when the remote unit is located remote from the base unit and requesting dial tone therefrom; comparing the predetermined signal code stored in the base unit with the signal code received from a remote unit requesting dial tone; and activating the base unit when the signal code received from the remote unit is found by the comparing step to be equivalent to the predetermined signal code stored in the base unit.
Claim 14
Independent Claim
238 words
A method of preventing unauthorized placing of telephone calls in a cordless telephone system over telephone lines associated with the system, the system including a base unit for connection to the telephone lines and for transmitting to and receiving signals from a remote unit associated with the base unit, the remote unit also transmitting to and receiving signals from the base unit, and the base unit being activatable by the remote unit to cause dial tone to be transmitted to the remote unit for placing a telephone call therefrom, the method CHARACTERIZED BY storing a predetermined signal code in the base unit for preventing the base unit from responding to an unauthorized remote unit; transmitting the predetermined signal code from the base unit and receiving the predetermined signal code in the associated remote unit over an electrical path established when the remote unit is brought in electrical contact with the base unit; storing the signal code by the remote unit for transmission back to the base unit when the remote unit is located remote from the base unit and requesting dial tone therefrom; comparing the predetermined signal code stored in the base unit with the signal code received from a remote unit requesting dial tone; and activating the base unit when the signal code received from the remote unit is found by the comparing step to be equivalent to the predetermined signal code stored in the base unit.
Claim 15
Dependent Claim
33 words
The method pursuant to claim 12 further CHARACTERIZED BY bringing into electrical contact the handset unit with the base unit by placing the remote unit in a mating cradle on the base unit.
Claim 16
Dependent Claim
34 words
The method pursuant to claim 12 further CHARACTERIZED BY storing a different predetermined signal code in the base unit each time the associated remote unit is brought into. electrical contact with the base unit.
Claim 17
Dependent Claim
56 words
The method pursuant to claim 14 wherein the storing step is further CHARACTERIZED BY generating a random number for use as the different predetermined signal code, the random number being stored in memory in a code select circuit for comparison by the comparing step with a signal code received from the remote unit requesting dial tone.
Claim 18
Dependent Claim
60 words
The method pursuant to claim 12 wherein the transmitting and receiving steps are CHARACTERIZED BY bring into electrical contact the remote unit and the base unit by a direct current charging path established when the remote unit is placed in a mating cradle in the base unit, the charging path being used for charging a battery in the remote unit.
Claim 19
Dependent Claim
68 words
The method pursuant .to claim 16 wherein in the base unit the transmitting step is further CHARACTERIZED BY - providing a signal indication to a control circuit in the base unit reflecting when the associated remote unit is brought into electrical contact with the base unit, and providing an activation signal for initiating the transmitting of the predetermined signal code from the control circuit to the remote unit.
Claim 20
Dependent Claim
55 words
The method pursuant to claim 17 wherein in the base unit the transmitting step is further CHARACTERIZED BY generating a serial data stream across the charging path by pulsing a transistor coupled to the control circuit and responsive thereto for transmitting the signal code over the electrical contact made by the direct current charging path.
Claim 21
Dependent Claim
87 words
The method pursuant to claim 16 wherein in the associated remote unit, the receiving step is further CHARACTERIZED BY providing a signal indication to a control circuit in the remote unit reflecting when the remote unit is brought into electrical contact with the base unit, the signal indication step providing an activation signal for switching the remote unit from a talk to a standby mode wherein the transmission of the predetermined signal code from the base unit to the control circuit in the remote unit is performed
Claim 22
Dependent Claim
35 words
The method pursuant to claim 19 wherein in the associated remote unit, the receiving step is further CHARACTERIZED BY transmitting an acknowledge signal back to the base unit for indicating receipt of the signal code.
Claim 23
Dependent Claim
38 words
21, The method pursuant to claim 20 CHARACTERIZED IN THAT the acknowledge signal is transmitted over the electrical contact made by the direct current charging path by pulsing the charging path off and on by the control circuit.
References Cited (Backward Citations)
No citation records indexed.
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