Issued Patents All Time
Showing 1–4 of 4 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 6959069 | Method for testing subscriber line of private automatic branch exchange using dual-tone multi-frequency signal | — | 2005-10-25 |
| 6480596 | Direct inward-outward dialing trunk circuit | — | 2002-11-12 |
| 6345096 | Central office line interfacing circuit | — | 2002-02-05 |
| 5930101 | Overvoltage cut-off circuit of private exchange branch having tie line | — | 1999-07-27 |