Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 8311033 | DTMF tone signal transmission method and DTMF tone signal transmission system | — | 2012-11-13 |
| 7508818 | IP telephony method and IP telephone system | — | 2009-03-24 |
| 7301937 | System for automatically selecting voice data transmission and reception system for IP network, method thereof, and IP terminal | Yoshikazu Kobayashi | 2007-11-27 |