Independentvolume, CDMA requirements for coding and encryption are based on 2005 Qualcomm Standards, while most US Carriers use the newer standards, especially a Verizon and Sprint which support SVDO (which requires 512bit encryption because it adds an extra radio to be used for data while on a voice call).
Brmiller needs to do more research on why most CDMA carriers and MVNOs are using 512bit encryption over the 256bit encryption. Go ahead and blame Sprint and Verizon for helping Qualcomm resolve the problem of not being able to talk and surf over 3G...