I'm cornfused. When I was a pre-iPhone Cingular customer, I had (something like) 800 family-talk rollover minutes, an extra cell & cell number for my wife, and a $50 data plan for my TreeStump 650. We shared the pool of rolloverminutes.
When I purchased the iPhone, on activiting it, as a Cingular customer, I was offered the opportunity to replace a phone on the current plan with the iPhone, and transfer the old phone (Treo's) number to the iphone. So I did.
"Did I agree to an additional $20 data charge on the plan?"
Sure. I didn't know what would happen to the $50 I was paying for the Treo, but I figured if they didn't get it right, AT&T would fix it.
So, my bill is now less by $30. And I kept our old rollover minutes. And the Treo is an ugly paperweight.
I did NOT have to change plans, and anyone who tells you different has never activated an iPhone via iTunes.
-- Mikie