Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04Q—SELECTING
  • H04Q1/00—Details of selecting apparatus or arrangements
  • H04Q1/18—Electrical details
  • H04Q1/30—Signalling arrangements; Manipulation of signalling currents
  • H04Q1/38—Signalling arrangements; Manipulation of signalling currents using combinations of direct currents of different amplitudes or polarities over line conductors or combination of line conductors
• • 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
  • H04M9/005—Arrangements for interconnection not involving centralised switching with subscriber controlled access to a line, i.e. key telephone systems with subscriber controlled access to an exchange line

Landscapes

• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Interconnected Communication Systems, Intercoms, And Interphones (AREA)
• Sub-Exchange Stations And Push- Button Telephones (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=5897687

Family Applications (1)

Country Status (8)

• 1973
  • 1973-11-09 DE DE19732356095 patent/DE2356095C3/de not_active Expired
• 1974
  • 1974-10-31 AU AU74904/74A patent/AU7490474A/en not_active Expired
  • 1974-11-04 NL NL7414330A patent/NL7414330A/xx unknown
  • 1974-11-06 DK DK577074A patent/DK577074A/da unknown
  • 1974-11-07 IT IT2917974A patent/IT1025484B/it active
  • 1974-11-07 FR FR7436907A patent/FR2251141B1/fr not_active Expired
  • 1974-11-08 BE BE2053967A patent/BE821977R/xx not_active IP Right Cessation
  • 1974-11-08 ES ES431772A patent/ES431772A1/es not_active Expired

Also Published As

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