Go to settings > phone info > icon glossy. Then scroll down and look for voice privacy. There is a little "p" icon.
I have voice privacy turned on. (don't really know what it does, but it is on)
When make a phone call, why don't I get a "P" in the status bar? In fact, I never have seen that P light up.
On the other hand, lets take a look at the "S" for secure - If bring up My Verizon, the "S" lights up in the top to tell me it is secure.....so when I make a phone call, why don't I get a P for Privacy?
Actually, voice privacy on CDMA is an added layer of voice encryption. Sprint did some independent research (I've heard quotes as big as a million dollars worth) and determined that CDMA without Voice Privacy is just as secure (unless you've got a million dollars worth of financing to break into an individual phone call)...
In other words, turn the feature off, and don't worry about it.