GB1371120A – Apparatus for blocking the dialling operation of a subscriber telephone set
– Google Patents
GB1371120A – Apparatus for blocking the dialling operation of a subscriber telephone set
– Google Patents
Apparatus for blocking the dialling operation of a subscriber telephone set
Info
Publication number
GB1371120A
GB1371120A
GB4754072A
GB4754072A
GB1371120A
GB 1371120 A
GB1371120 A
GB 1371120A
GB 4754072 A
GB4754072 A
GB 4754072A
GB 4754072 A
GB4754072 A
GB 4754072A
GB 1371120 A
GB1371120 A
GB 1371120A
Authority
GB
United Kingdom
Prior art keywords
digit
logic
dialled
circuit
exchange
Prior art date
1971-12-17
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB4754072A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Italtel SpA
Original Assignee
Societa Italiana Telecomunicazioni Siemens SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1971-12-17
Filing date
1972-10-16
Publication date
1974-10-23
1971-12-17
Priority claimed from IT3258471A
external-priority
patent/IT944106B/en
1972-10-16
Application filed by Societa Italiana Telecomunicazioni Siemens SpA
filed
Critical
Societa Italiana Telecomunicazioni Siemens SpA
1974-10-23
Publication of GB1371120A
publication
Critical
patent/GB1371120A/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
Classifications
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/66—Substation equipment, e.g. for use by subscribers with means for preventing unauthorised or fraudulent calling
H04M1/677—Preventing the dialling or sending of predetermined telephone numbers or selected types of telephone numbers, e.g. long distance numbers
Abstract
1371120 Automatic exchange systems SOC ITALIANA TELECOMUNICAZIONI SIEMENS SpA 16 Oct 1972 [17 Dec 1971] 47540/72 Heading H4K A substation includes a logic circuit which in the event of a prohibited first digit, e.g. “0” or “9” being dialled or of dialling being attempted before the arrival of dial tone or of a short pulse being dialled, causes further impulse transmission to be inhibited. The short pulse of typically less than 35 msec. duration would not be recognized by exchange equipment but could trigger the local digit counter into believing that a permitted first digit has been dialled thereby permitting an unauthorized code to be subsequently transmitted. Short pulses also occur if the user dials a digit 10-N and then actuates his switchhook N times in an attempt to dial “0”. The exchange would probably recognize the digit “0” even though the “N” portion thereof comprises relatively short makes and breaks. If the logic responds to any of the above eventualities it operates a bi-stable circuit which causes a locally generated busy tone to be injected into the subset circuit and connects a low impedance chain across the live wires during impulsing. A busy tone detector includes a guard circuit responsive to a speech or noise frequency, e.g. 1600 Hz so as to enable the subset to dispense with the handset shortcircuiting arrangement disclosed in Specification 1,360,038. Impulses applied to line by the subset dial are squared and integrated (thereby eliminating impulses of less than 8 ms.) before being applied to the logic circuit. Impulse transmission is prevented if the subscriber simulates a so-called “users-tone” by juggling his hook switch (this in effect clears the exchange register first seized but does not clear the logic circuit’s impression that a permissible first digit has been dialled). At the substation the temporary break in the current supply as a new register is switched into the connection is recognized by the logic so as to inhibit further transmission. On the other hand, the failure of current supply which sometimes occurs after a full dialling sequence is not effective to trigger the logic into turning on the local busy tone.
GB4754072A
1971-12-17
1972-10-16
Apparatus for blocking the dialling operation of a subscriber telephone set
Expired
GB1371120A
(en)
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
IT3258471A
IT944106B
(en)
1970-12-17
1971-12-17
PROCEDURE FOR THE PREPARATION OF ACRYLATE AND METHACRYLATE ESTERS FROM UNSATURATED ORGANIC COMPOUNDS
Publications (1)
Publication Number
Publication Date
GB1371120A
true
GB1371120A
(en)
1974-10-23
Family
ID=11235507
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB4754072A
Expired
GB1371120A
(en)
1971-12-17
1972-10-16
Apparatus for blocking the dialling operation of a subscriber telephone set
Country Status (4)
Country
Link
US
(1)
US3899640A
(en)
DE
(1)
DE2261906C3
(en)
ES
(1)
ES403458A1
(en)
GB
(1)
GB1371120A
(en)
Families Citing this family (10)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US4177358A
(en)
*
1974-09-16
1979-12-04
Mason John W
Tone dial toll restrictor
US4012602A
(en)
*
1975-03-14
1977-03-15
Litton Business Telephone Systems, Inc.
Toll restrictor for touch type digit selector
US3980836A
(en)
*
1975-05-05
1976-09-14
International Components Corporation
Toll restricting method and apparatus
US4092500A
(en)
*
1976-08-30
1978-05-30
Hughes George W
Device for selectively interrupting mechanical operation of a manually operated telephone
JPS5383402A
(en)
*
1976-12-28
1978-07-22
Tamura Electric Works Ltd
Dial number control system
US4124781A
(en)
*
1977-08-31
1978-11-07
Akzona Incorporated
Telephone toll restrictor
US4209668A
(en)
*
1978-09-20
1980-06-24
Utility Verification Corp.
Telephone having reiterative dialing feature
US4251692A
(en)
*
1978-10-06
1981-02-17
Waldman Herbert H
Telephone call restricting apparatus
US6700963B1
(en)
*
1998-04-08
2004-03-02
Worldcom, Inc.
System and method therefor of preventing fraud on pay phone credit/debit calling card authorization
CA2279684C
(en)
*
1999-08-05
2007-05-15
Vtech Communications, Ltd.
Method and apparatus for telephone call fraud detection and prevention
Family Cites Families (3)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US3651275A
(en)
*
1969-11-24
1972-03-21
Bell Telephone Labor Inc
Toll diverting circuit
CH537677A
(en)
*
1970-10-06
1973-05-31
It Telecommunicazioni Siemens
Blocking device for remote dialing and taxed services in general for user telephone sets
US3748396A
(en)
*
1971-04-14
1973-07-24
Itt
Direct inward dialing trunk circuit
1972
1972-05-20
ES
ES403458A
patent/ES403458A1/en
not_active
Expired
1972-10-16
GB
GB4754072A
patent/GB1371120A/en
not_active
Expired
1972-12-18
US
US315892A
patent/US3899640A/en
not_active
Expired – Lifetime
1972-12-18
DE
DE2261906A
patent/DE2261906C3/en
not_active
Expired
Also Published As
Publication number
Publication date
DE2261906A1
(en)
1973-07-05
DE2261906B2
(en)
1981-02-19
ES403458A1
(en)
1975-05-01
US3899640A
(en)
1975-08-12
DE2261906C3
(en)
1981-11-26
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Legal Events
Date
Code
Title
Description
1975-03-05
PS
Patent sealed [section 19, patents act 1949]
1982-05-26
PCNP
Patent ceased through non-payment of renewal fee
