JPS551751A - Zero call prevention unit - Google Patents

Zero call prevention unit

Info

Publication number
JPS551751A
JPS551751A JP7454978A JP7454978A JPS551751A JP S551751 A JPS551751 A JP S551751A JP 7454978 A JP7454978 A JP 7454978A JP 7454978 A JP7454978 A JP 7454978A JP S551751 A JPS551751 A JP S551751A
Authority
JP
Japan
Prior art keywords
telephone
circuit
zero
extension
telephone set
Prior art date
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.)
Pending
Application number
JP7454978A
Other languages
Japanese (ja)
Inventor
Yoichi Kodama
Tomotake Kawakami
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.)
TAMAGAWA DENKI SEISAKUSHO KK
Original Assignee
TAMAGAWA DENKI SEISAKUSHO KK
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.)
Filing date
Publication date
Application filed by TAMAGAWA DENKI SEISAKUSHO KK filed Critical TAMAGAWA DENKI SEISAKUSHO KK
Priority to JP7454978A priority Critical patent/JPS551751A/en
Publication of JPS551751A publication Critical patent/JPS551751A/en
Pending legal-status Critical Current

Links

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

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Signal Processing (AREA)

Abstract

PURPOSE:To prevent the toll call from extension telephone sets economically, by detecting the extension telephone set for zero dial pulse delivery first, and disconnecting compulsively the connection between the extension and the telephone line at the detection of the zero pulse. CONSTITUTION:The counter circuit 7 which counts the constituent pulse number of the dial pulse signal delivered first on the two wire telephone line 13 from an extention telephone set, is provided. When the value counted with the circuit 7 is equal to the number of constituent pulses of the signal corresponding to the zero of the telephone number, the number of pulses is latched on the latch circuit 8, the relay drive circuit 9 is activated and the relay contact circuit 10 is disconnected to disconnect the telephone set and the telephone line 13. Further, this disconnection is released with the output of the restorasion signal generating circuit 11 when the hook switch in the telephone set is open, to prevent the toll call from the extension telephone sets.
JP7454978A 1978-06-20 1978-06-20 Zero call prevention unit Pending JPS551751A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7454978A JPS551751A (en) 1978-06-20 1978-06-20 Zero call prevention unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7454978A JPS551751A (en) 1978-06-20 1978-06-20 Zero call prevention unit

Publications (1)

Publication Number Publication Date
JPS551751A true JPS551751A (en) 1980-01-08

Family

ID=13550433

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7454978A Pending JPS551751A (en) 1978-06-20 1978-06-20 Zero call prevention unit

Country Status (1)

Country Link
JP (1) JPS551751A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2821425A1 (en) * 1977-05-19 1978-11-23 Matsushita Electric Ind Co Ltd SPEED CONTROL SYSTEM FOR A SMALL DC ELECTRIC MOTOR

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50134708A (en) * 1974-04-15 1975-10-25

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50134708A (en) * 1974-04-15 1975-10-25

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2821425A1 (en) * 1977-05-19 1978-11-23 Matsushita Electric Ind Co Ltd SPEED CONTROL SYSTEM FOR A SMALL DC ELECTRIC MOTOR
DE2821425C2 (en) * 1977-05-19 1983-11-03 Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka Circuit arrangement for regulating the speed for a DC motor of small design

Similar Documents

Publication Publication Date Title
US4072827A (en) Telephone patching apparatus
US3514544A (en) Party line privacy device
JPS57168567A (en) Electric power feeding system
US3784756A (en) Subscriber loop range extender
US4365117A (en) Telephone hold circuit
US4496797A (en) Circuit for automatically connecting and disconnecting a speakerphone to a telephone line
JPS551751A (en) Zero call prevention unit
CA2042682A1 (en) Over-current detector circuit for an enhanced subscriber line interface
US3626101A (en) Loop extender for subscribers connected to a central office by abnormally long telephone lines
CA1203331A (en) Latching relay hold release circuit for a telephone instrument
US3374317A (en) Telephone signaling system
US4009354A (en) Signalling device for key telephone systems
US3322903A (en) Telephone signaling system
US3934098A (en) Telephone message transfer circuit
US3430002A (en) Compatible multifrequency direct current telephone signal receiver
JPS5725756A (en) Call signal detector
JPS57145466A (en) Switchboard
US4017692A (en) Telephone call-diverter system
KR860000882B1 (en) A telephone circuit
JPS55161453A (en) Toll call preventing unit
US3748404A (en) Telephone line circuit embodying a triggerable avalanche device
SU407362A1 (en) DEVICE FOR ALARM ALARM
JPS55165062A (en) Monitor circuit for ground connection of public telephone set
JPS551790A (en) Automatic response unit for automatic answering telephone
JPS551789A (en) Automatic response unit for automatic answering telephone