Call progress signal detector
CA 1067632 A · Owner: International Business Machines Corporation · Inventors: Soo, Suk S.; Brennemann, Andrew E.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract of the Disclosure This invention relates to apparatus for automatically connecting computer terminals and the like to telephone lines and further includes means for automatically analyzing telephone line call progress signals indicative of line status. The apparatus includes a band pass filter, variable gain amplifier AM detector, a wave shaper, a signal cadence detector and means responsive to said cadence detector for indicating line status.
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 December 4, 1979. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended December 4, 1996.
- 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.