The carrier’s CEO had previously said that HD Voice’s nationwide rollout is on the cards for this summer, “around the first of July” to be precise. Sprint HD Voice is already being tested in several markets, with the nationwide rollout the carrier aims to cover majority of U.S. markets. Hesse believes that Voice is “still the killer app” for selling smartphones and also attracting new subscribers.
HD Voice doesn’t work though if both participants aren’t using compatible smartphones. That’s because it utilizes Adapted Multi-Rate Wide Band codec for encoding phone calls. This codec effectively enlarges range of sound carried by the call, from 300Hz to 2,400Hz range to a much wider 50Hz to 7,000Hz spread. The result is double the bandwidth used for a conventional 3G call, its claimed that this improves voice quality by as much as 40 percent.