GB491612A - Improvements in or relating to telephone systems - Google Patents

Improvements in or relating to telephone systems

Info

Publication number
GB491612A
GB491612A GB1282937A GB1282937A GB491612A GB 491612 A GB491612 A GB 491612A GB 1282937 A GB1282937 A GB 1282937A GB 1282937 A GB1282937 A GB 1282937A GB 491612 A GB491612 A GB 491612A
Authority
GB
United Kingdom
Prior art keywords
line
loop
current
indicator
called subscriber
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.)
Expired
Application number
GB1282937A
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.)
Ericsson Telephones Ltd
Original Assignee
Ericsson Telephones 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 Ericsson Telephones Ltd filed Critical Ericsson Telephones Ltd
Priority to GB1282937A priority Critical patent/GB491612A/en
Publication of GB491612A publication Critical patent/GB491612A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements
    • H04Q3/58—Arrangements providing connection between main exchange and sub-exchange or satellite
    • H04Q3/62—Arrangements providing connection between main exchange and sub-exchange or satellite for connecting to private branch exchanges
    • H04Q3/625—Arrangements in the private branch exchange

Landscapes

  • Physics & Mathematics (AREA)
  • Astronomy & Astrophysics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

491,612. Exchange systems. ERIC. SSON TELEPHONES, Ltd., and DISTIN, L. S. May 5, 1937, No. 12829. [Class 40 (iv)] A supervisory relay is connected in series with the line and is associated with a fullwave rectifier so that it responds to prolonged interruptions of the line current, but not to current reversals or dialled impulses. In the system shown, the operator at a cordless P.B.X. switchboard sets up an outgoing call by looping the junction via keys KA, KS and dialling in the usual way, and completes it to the calling subscriber by operating a key such as KE. Supervisory relay S is associated with the line and with a rectifier bridge so that it remains operated continuously and holds indicator IR disconnected until the calling party hangs up. Incoming ringing current operates an indicator ID which locks up. When the call is answered, S pulls up over the loop in the operators' circuit, releases ID and subsequently holds over the called subscriber's loop to keep IR disconnected until the called subscriber hangs up.
GB1282937A 1937-05-05 1937-05-05 Improvements in or relating to telephone systems Expired GB491612A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB1282937A GB491612A (en) 1937-05-05 1937-05-05 Improvements in or relating to telephone systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1282937A GB491612A (en) 1937-05-05 1937-05-05 Improvements in or relating to telephone systems

Publications (1)

Publication Number Publication Date
GB491612A true GB491612A (en) 1938-09-06

Family

ID=10011898

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1282937A Expired GB491612A (en) 1937-05-05 1937-05-05 Improvements in or relating to telephone systems

Country Status (1)

Country Link
GB (1) GB491612A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2875285A (en) * 1957-04-30 1959-02-24 Earle D Hightower Detector for telephone surreptitious listening techniques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2875285A (en) * 1957-04-30 1959-02-24 Earle D Hightower Detector for telephone surreptitious listening techniques

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