Sprint won't be supporting HD Voice on the iPhone 5
A brief chunk of today's iPhone 5 event was dedicated to the new smartphone's support for "wideband audio" phone calls. What wideband audio offers is phone calls with audio that's been less compressed than your typical cell phone call. The average cell phone emphasizes the mid-range where most of your voice pitch resides, and heavily compresses and thus distorts the higher and lower ranges. Wideband audio still applies some compression, but it's not as harsh on the upper and lower frequencies, offering a wider range of pitch and thus more lifelike sound. It also enhanced noise cancellation and makes it easier to differentiate what you're listening to.
Unless you're on Sprint, which apparently won't support wideband audio on the iPhone 5. According to a statement given to Phone Scoop by Sprint, the Now Network won't be offering their HD Voice service (the marketing name for wideband audio voice) on the iPhone 5.
No specific reasoning was given why Sprint won't be one of the claimed twenty carriers globally that will be supporting wideband audio on the iPhone 5. Sprint does offer HD Voice on the Android-powered HTC Evo 4G LTE, though like Sprint's LTE network, only select markets will have HD Voice support by the end of the year.
We don't know what other carriers might offer support for wideband audio on the iPhone 5, but considering the dozens and dozens of carriers that will offer the device, it's disappointing to only hear the number twenty. Verizon's own HD Voice tinkering has been done using VOLTE (Voice Over LTE), which Apple doesn't support. AT&T hasn't tinkered with HD Voice yet, but they'll be doing it over VOLTE as well.
Sure, we don't make phone calls as often as we used to, but when we do we'd love for them to be sounding better than they currently do.
Source: Phone Scoop