Telephone line message waiting and ring indicator
CA 2078389 C · Owner: Nortel Networks Limited · Inventors: Lee, Allan Yook Foo
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A visual indicator circuit is provided for visually indicating that a telephone is ringing or that a message is waiting. The circuit includes a visual indicator such as a light emitting diode (LED) a voltage, triggering circuit for triggering when a minimum predetermined voltage is applied to the telephone lines and a current limiting circuit for limiting the current provided to the LED.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed September 16, 1992 and granted December 8, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 16, 2012.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 16, 2014.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.