As promised, Sprint(s s) has turned its high-definition voice network on across its nationwide 2G service. The technology, which improves the quality and audio range of standard mobile voice calls, is now supported on 28 postpaid and 33 prepaid smartphones, and Sprint estimates about 16 million customers are already using an HD-capable device.

Sprint revealed the news at a launch event at Chicago’s Museum of Broadcast Communications on Monday, along with a slew of other announcements, including a new exclusive phone, the Galaxy S5 Sport. Fitness was actually a big theme of the day, as Sprint unveiled a new application skin for the device and other smartphones focused on exercise and health. Sprint also launched a new service called “Framily Wall,” a kind of family social network and collaboration tool.

Sprint will have an exclusive on the new GS5 Sport (Photo: Kevin Fitchard)

The HD nationwide voice rollout will…