I was taking a look at some of the features of the ZTE V8000, and I noticed HD Voice was on the list. I remember reading something about HD Voice with Sprint, so I thought I'd search for Cricket and HD Voice on Google, and the following article came up, which I thought was interesting:
Leap/Cricket getting lots of CDMA 1X Advanced; will HD voice be there? « HD Voice News

At CTIA’s show this week, Leap Wireless was underlining its commitment to CDMA 1X Advanced technology. The company plans to have the HD voice-enabling tech in all of its new phones, with a bunch of 1X Advanced models coming out in the second half of 2012. But no word if it will use the CDMA upgrade to provide HD voice service.Offering pre-paid service through its Cricket subsidiary, Leap initially announced its commitment to incorporating 1X Advanced in January. The Huawei Mercury, introduced in January, is among the current crop of Cricket phones that incorporate 1X Advanced technology. More devices will be rolled out between July and October.The big question is how Leap will use CDMA 1X Advanced. The technology along with Qualcomm’s EVRC-NW can be used to either deliver HD voice in the same RF bandwidth as a current CDMA narrowband call or used to refarm/repackage spectrum, delivering narrowband calls in about a third of existing spectrum usage."