It was in fall of 2002 just when the development of the indoor device for telecommunication carriers was reaching completion. I was beginning to feel that there would be a new change in terms of communication quality when looking at the pattern of networks becoming full IP, and broadband lines spreading. This confirmed my belief for the latter of the two hypotheses mentioned previously: the hypothesis of improved communication quality.

When the ISDN network was being established, complete digitalization of the telephone network was the goal. In the case of ISDN, the infrastructure was structured by communication devices of various tiers. But the wall of "300 ~ 3.4kHz band" for voice existing from the early days could not be conquered. There was a concept of high-grade telephone even with ISDN and development was also made. In order to overcome the wall of the "300 ~ 3.4kHz band" restriction, however, all transmission networks had to be converted to broadband. This was not an easy wall to overcome to say the least.

In comparison, the infrastructure of an IP network is unbelievably simple, making it that much easier to overcome the wall needed to change voice quality. With networks moving into the direction of IP, I felt that now was the perfect time to improve voice quality using the characteristics of IP and changing the quality of communication.

We came to firmly believe that the wall of conventional telephone voice quality can be brought down by utilizing the potential of IP networks.

Hint from a broadband chip

Just when I was expanding such an idea, an opportunity to fully accelerate the verification of this hypothesis fell in our hands. And of all places, it came from the device vendor in the U.S. which we shared the pleasure and pain with during the development of the indoor device. I was given a single data sheet from a person in charge at the vendor's agency after a particular meeting.

"We have this chip..."

It was a data sheet introducing a subscriber circuit allowing a broad bandwidth to pass through.

Although I tried to not show it, something rang a bell inside my head. But the person in charge at the agency continued in a quiet, reserved tone, "Any chance you can make use of this for something?"

I asked, "Have you ever heard actual voice using this?"
"No," she responded, "we never had a telephone that allows you to hear voice in broadband..."

At that instant, the high-grade telephone developed during the ISDN period crossed my mind. And the established theory is that a technology missing the wave of the trend and branded "no good" don't usually come back to see the light of day.