Issued Patents All Time
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4935956 | Automated public phone control for charge and collect billing | George A. Hellwarth, David C. Hellwarth, Jan G. Hellwarth | 1990-06-19 |
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4935956 | Automated public phone control for charge and collect billing | George A. Hellwarth, David C. Hellwarth, Jan G. Hellwarth | 1990-06-19 |