Combined telephone and protective alarm system.

Read the whole patent

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.

Why it's free to use

• Granted December 28, 1909. A patent granted before 1976 lasted at most 17 years from grant, so its term ended by December 28, 1926.
• We check US rights only. Old patents can still inspire new ones: improvements may be patentable.