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
  • H04Q1/44—Signalling arrangements; Manipulation of signalling currents using alternate current
  • H04Q1/444—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies
  • H04Q1/446—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency
  • H04Q1/4465—Signalling arrangements; Manipulation of signalling currents using alternate current with voice-band signalling frequencies using one signalling frequency the same frequency being used for all signalling information, e.g. A.C. nr.9 system
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M1/00—Substation equipment, e.g. for use by subscribers
  • H04M1/64—Automatic arrangements for answering calls; Automatic arrangements for recording messages for absent subscribers; Arrangements for recording conversations
  • H04M1/65—Recording arrangements for recording a message from the calling party
  • H04M1/654—Telephone line monitoring circuits therefor, e.g. ring detectors

Applications Claiming Priority (1)

Publications (1)

Family

ID=4526497

Family Applications (1)

Country Status (3)

• 0
  • NL NL67819D patent/NL67819C/xx active
• 1946
  • 1946-01-29 CH CH266521D patent/CH266521A/en unknown
• 1947
  • 1947-01-28 GB GB2655/47A patent/GB655937A/en not_active Expired

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