3689705

Information

• Patent Grant
• 3689705

• References
• Source

• Patent Number

  3,689,705

• Date Filed

  Not available

• Date Issued

  Tuesday, September 5, 1972
  51 years ago

• CPC

  • H04M19/02 - providing ringing current or supervisory tones
  • H04Q5/08 - Signalling by continuous ac

• US Classifications

  • 379 - Telephonic communications