Alert method for cordless telephones
CA 2106342 C · Owner: Schellinger, Michael J. · Inventors: Sherman, Charles L.; Schellinger, Michael J.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The method of the present invention controls the alert generation of a cordless telephone, thus synchronizing all cordless telephones at a particular number. The base unit of the cordless telephone sends a ring start message in the subaudible message stream to the handset unit. The handset then monitors the audible portion of the channel for a tone. Upon reception of the tone the alert is generated until the, handset receives the sub-audible ring stop message from the base unit.
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, 1993 and granted January 21, 1997. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended September 16, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by September 16, 2015.
- 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.