{
  "patent_number": "US 447918",
  "country": "US",
  "title": "How Almon Strowger Invented the Automatic Telephone Switch",
  "original_title": "Automatic telephone-exchange",
  "summary": "An 1891 patent for an automatic telephone exchange that allowed callers to connect to each other without needing a human operator.",
  "what_it_does": "This patent describes a mechanical switching system that replaced manual telephone operators. It uses a series of electrical impulses sent from a user's telephone to move a contact arm across a grid of terminals. By counting the pulses, the system physically rotates and lifts the arm to land on the specific wire connected to the desired recipient. This allowed a caller to establish a direct connection to another subscriber through a series of electromagnetic relays.",
  "what_it_does_not_cover": [
    "Does not cover electronic or digital switching systems used in modern networks",
    "Does not cover software-based call routing or VoIP technology",
    "Does not cover systems that do not rely on physical, mechanical movement of contact arms"
  ],
  "filed": null,
  "granted": "1891-03-10",
  "expires": null,
  "status": "active",
  "holder": "Almon B. Strowger",
  "holder_url": "https://patentbrief.org/company/almon-b-strowger",
  "inventors": [],
  "times_cited": 70,
  "tags": [
    "telecommunications",
    "mechanical"
  ],
  "abstract": null,
  "url": "https://patentbrief.org/patent/us/447918/strowger-automatic-telephone-exchange",
  "markdown_url": "https://patentbrief.org/patent/us/447918/strowger-automatic-telephone-exchange/md",
  "google_patents_url": "https://patents.google.com/patent/US447918",
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}