1673661

Information

• Patent Grant
• 1673661

• References
• Source

• Patent Number

  1,673,661

• Date Filed

  Not available

• Date Issued

  Tuesday, June 12, 1928
  97 years ago

• CPC

  • H04M5/12 - Ringing or otherwise calling substations

• US Classifications

  • 381 - Electrical audio signal processing systems and devices
  • 181 - Acoustics