First, we attempted to verify the algorithm using actual devices. As explained previously, accommodating PHS is basically the same as guaranteeing synchronous communication on an IP network. It was an extremely difficult technical task. Verifications of the actual device helped play a critical role of establishing this technology. We repeated endlessly the steps of finding algorithm error, fixing the error and performing verification again using actual devices.

When developing a new product by applying a basic method that has already been established in an existing product, verification items tend to shift very little from what is first expected. However, verifications from the basic method require more time effort than one would expect. This verification was no different.

Some could not understand the need to incorporate a system for synchronization on LAN. But in order to realize the basic concept of integrating intra-office communication on LAN and IP networks, we did not have a choice. With such thoughts in our minds, we repeated the verification with much time and labor. And as a result, the level of the algorithm for synchronization in an asynchronous network was gradually reaching perfection. However, there was yet another task we had to overcome to accommodate full PHS support.

Difficulty in finding a location for PHS verification

The algorithm was near completion and the system for synchronizing PHS communication among units placed on a LAN was finished. However, the system of synchronization takes some time before it becomes stable. Hence, completely identical operation as a conventional line exchange network could not be guaranteed. Since time is required for the system to become stable, we needed to verify how such time would influence the actual operation of PHS. Since we had performed development of a PHS system for offices at OKI in the past, I first thought that we could easily perform verification using the same development environment.