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Telephone-exchange system

US 1,439,735 A · Inventors: WATT HANCOCK EDMUND

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Listed from its USPTO record in Patent Yard's full-term archive. Its claims, description and drawings are in the USPTO PDF and on Google Patents, and the Claude kit works from them.

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Why it's free to use

  • Granted December 26, 1922. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by December 26, 1939.
  • We check US rights only. Old patents can still inspire new ones: improvements may be patentable.
FiledOctober 20, 1920
GrantedDecember 26, 1922
Term endedDecember 26, 1939
Application number—
Classification (CPC)H04Q3/0016
Length62 pages

Timeline

Timeline From USPTO dates

1921192319251927192919311933193519371939Application filedOct 20, 1920Patent grantedDec 26, 1922Term endedDec 26, 1939

Sources & verification

Official USPTO records

Full published documentText and every drawing sheet as a PDF.USPTOFile historyStatus, office actions, notices, fee records and petitions.USPTO Patent CenterPatent Public Search recordSearchable full text and bibliographic data.USPTO

Cross-check elsewhere

Google PatentsFull text, worldwide family, citing patents and legal events.patents.google.comJustia PatentsFull text, claims and classification.patents.justia.comFreePatentsOnlineFull text and PDF.freepatentsonline.comEspacenetForeign family and legal status.European Patent Office

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