Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M11/00—Telephonic communication systems specially adapted for combination with other electrical systems
  • H04M11/04—Telephonic communication systems specially adapted for combination with other electrical systems with alarm systems, e.g. fire, police or burglar alarm systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M1/00—Substation equipment, e.g. for use by subscribers
  • H04M1/02—Constructional features of telephone sets
  • H04M1/18—Telephone sets specially adapted for use in ships, mines, or other places exposed to adverse environment
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04M—TELEPHONIC COMMUNICATION
  • H04M1/00—Substation equipment, e.g. for use by subscribers
  • H04M1/26—Devices for calling a subscriber
  • H04M1/515—Devices for calling a subscriber by generating or selecting signals other than trains of pulses of similar shape, or signals other than currents of one or more different frequencies, e.g. generation of dc signals of alternating polarity, coded pulses or impedance dialling

Landscapes

• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Telephonic Communication Services (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10509588

Family Applications (1)

Country Status (2)

• 1979
  • 1979-12-04 GB GB7941732A patent/GB2066022A/en not_active Withdrawn
• 1980
  • 1980-12-04 BR BR8007949A patent/BR8007949A/pt not_active IP Right Cessation

Also Published As

Similar Documents

Legal Events