Expired Canadian patentCanada
Multiple line self-contained telephone
CA 1237210 A · Owner: Lott, Thomas M. · Inventors: Lott, Thomas M.
Overview
Drawings and full text
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A novel detection circuit is provided for indicating whether a telephone line is in use or is available or is on hold. The simplified circuit can be incorporated within a telephone instrument so that no external circuitry is required.
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
- Granted May 24, 1988. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended May 24, 2005.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledJune 12, 1985
GrantedMay 24, 1988
Term endedMay 24, 2005
Patent numberCA 1237210 A
Classification (IPC)H04M7/00 +2 more
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.