XConnect's recently announced plan for a trial HD voice peering federation marks a significant advance in the move to HD communication. The trial, to take place between April and June of this year, will directly connect providers offering HD voice services. That will let them pass HD calls, which provide audio quality superior to that of conventional PSTN phone calls, to one another rather than just among their own customers. The trial thus represents an effort to start building a critical mass of HD-capable voice subscribers. As such, it is as much a commercial effort as a technical one.