Key telephone system with enhanced connectivity
CA 2035357 C · Owner: Northern Telecom Limited · Inventors: Wiebe, Charles Richard
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A key telephone system which is operably responsive to digitally encoded service orders and instructions stored in a ROM of a switching facility in a local ISDN telephone exchange achieves enhanced connectivity by using a dedicated line that provides a digital signaling and supervision communications path which is exclusively an ISDN basic rate OB+D teleservice channel. A key switch unit of the system is connected to the exchange by POTS lines to provide conventional voice analog services to a plurality of its subscriber stations. Interfacing the key switch unit with the teleservice channel, a personal computer translates data downloaded from the switching facility into instructions …
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 January 31, 1991 and granted January 9, 1996. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 31, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 31, 2013.
- 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.