Distinctive ringing and distinctive call-waiting tones in an isdn
CA 2242007 C · Owner: Zhang, Genzao · Inventors: Zhang, Genzao; Dowlatshahi, Shahram; Sandler, Howard Martin
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In a multi-service wireless, or wired, integrated services digital network the type-of-call information in a call setup message is used at the called station to generate a distinctive ring or distinctive call-waiting tone indicating the type of call.
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 November 17, 1997 and granted May 21, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 17, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 17, 2019.
- 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.