Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4769835 | Method of and circuit arrangement for inserting dialling intervals between stored dialling digits | Peter Hirth, Werner Frerichs | 1988-09-06 |
| 4723275 | Circuit arrangement for generating an acoustic ringing signal in a subscriber telephone set | Peter Hirth, Werner Frerichs | 1988-02-02 |