Was curious to see if anybody knew if there would be any changes to my account if I switched from a Black Berry to a PDA data account?

It appears that AT&T has equal $$ rate plans for the BlackBerry's and other PDA devices.

What I am worried about is if there will be any changes to my voice plan if I switched from a Black Berry to a Treo. I have quite a bit of rollover minutes that I don't want to lose if I make the switch. My current contract is only less than 6 months old, and will be paying the non-contract price for the Treo.