Hi Toni,
Another Cingular customer here. All of my cell phone bills list both outgoing calls AND incoming calls. Each outgoing call listing shows the city and number to which the call was made, as well as the duration of the call. Each incoming call listing shows "Incoming Cl" and the number called from, as well as the duration of the call. Very detailed. I don't understand why Sprint wouldn't do that. "Security reasons" doesn't make any sense, b/c when someone calls you on your cell phone the number of the caller shows up on your phone and is then entered into the call log on your cell phone. A few times I have received a call showing the caller as "Private," so I assume there is a way for the individual caller to block his/her number for security reasons.
I would suggest that the next time you call Sprint, you keep going up the chain of command until you speak with someone who will answer your question.
MissL