3842216

Information

• Patent Grant
• 3842216

• References
• Source

• Patent Number

  3,842,216

• Date Filed

  Not available

• Date Issued

  Tuesday, October 15, 1974
  50 years ago

• CPC

  • H04Q1/446 - using one signalling frequency
  • H04M1/82 - Line monitoring circuits for call progress or status discrimination

• US Classifications

  • 379 - Telephonic communications