JPS55147866A - Extension circuit of key telephone unit - Google Patents

Extension circuit of key telephone unit

Info

Publication number
JPS55147866A
JPS55147866A JP5546579A JP5546579A JPS55147866A JP S55147866 A JPS55147866 A JP S55147866A JP 5546579 A JP5546579 A JP 5546579A JP 5546579 A JP5546579 A JP 5546579A JP S55147866 A JPS55147866 A JP S55147866A
Authority
JP
Japan
Prior art keywords
circuit
calling
extension
telephone set
called
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
JP5546579A
Other languages
Japanese (ja)
Inventor
Tatsuya Kato
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.)
NEC Corp
Original Assignee
NEC Corp
Nippon Electric Co Ltd
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 NEC Corp, Nippon Electric Co Ltd filed Critical NEC Corp
Priority to JP5546579A priority Critical patent/JPS55147866A/en
Publication of JPS55147866A publication Critical patent/JPS55147866A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M9/00—Arrangements for interconnection not involving centralised switching
    • H04M9/002—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Sub-Exchange Stations And Push- Button Telephones (AREA)

Abstract

PURPOSE:To obtain an extension circuit where constitution is comparatively simple as the extension circuit of the key telephone unit and hand-free answer back is possible, by using the speaker in the key telephone set as a microphone also. CONSTITUTION:In a calling telephone set, a calling signal is sent from calling circuit 36 by the extension calling operation to drive called detecting circuit 25 of the called telephone set through extension control circuit 5 of the main unit, and further, called switch 26 is made to form a sound loop. Next, extension calling sound is spoken loudly from transmitter and receiver 35 by the loop passing through loss inserting circuit 6 and amplifying circuit 7. Next, for answer back to speaker 27 of the called subscriber, sound is converted to an electric signal and is sent to transmitter and receiver 35 of the calling telephone set by the loop passing through loss inserting circuit 10 and amplifying circuit 11.
JP5546579A 1979-05-07 1979-05-07 Extension circuit of key telephone unit Pending JPS55147866A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP5546579A JPS55147866A (en) 1979-05-07 1979-05-07 Extension circuit of key telephone unit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5546579A JPS55147866A (en) 1979-05-07 1979-05-07 Extension circuit of key telephone unit

Publications (1)

Publication Number Publication Date
JPS55147866A true JPS55147866A (en) 1980-11-18

Family

ID=12999349

Family Applications (1)

Application Number Title Priority Date Filing Date
JP5546579A Pending JPS55147866A (en) 1979-05-07 1979-05-07 Extension circuit of key telephone unit

Country Status (1)

Country Link
JP (1) JPS55147866A (en)

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