Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4313038 | DTMF Signal receiver | Spencer L. Hermanson | 1982-01-26 |
| 4219699 | Telephone supervision system using DTMF signals | Spencer L. Hermanson | 1980-08-26 |
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4313038 | DTMF Signal receiver | Spencer L. Hermanson | 1982-01-26 |
| 4219699 | Telephone supervision system using DTMF signals | Spencer L. Hermanson | 1980-08-26 |