Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4873718 | Feature telephone integration device | Douglas A. Welch, Duncan J. S. MacMillan, Jr. | 1989-10-10 |
| 4811381 | Direct inward dial integration apparatus | Donald E. Woo | 1989-03-07 |