US Patents

Check USPTO Database

Check Google Patents (better presentation)

Name	Filed	Granted	Number
Service Order Mechanism	1997	2000	6031904
Visual Caller Display	1996	1998	5761279
Party Line Circuits	1967	1970	3530253
Self Steering System	1968	1970	3521004
Call Offering	1967	1970	3501596

Canadian Patents

Check Canadian Patent Database

Name	Filed	Granted	Number
Self Steering System	1968	1971	864123
Party Line Circuits	1967	1970	834836
Call Offering	1967	1969	827243
Number Translator	1965	1967	763519