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Inventor
KAUFMAN DAVID D
US
2 patents
Patents
2 patents
US5187710A
Feb 16, 1993
Method and apparatus for the billing of value-added communications calls
AT & T BELL LAB
174 citations
94
US5003584A
Mar 26, 1991
Method and apparatus for the billing of value-added communication calls
AT & T BELL LAB
406 citations
92