I don't have a pre, but I want to get to the bottom of this. The interwebs is saying that this is enabled by default, not by user prompt. Can you clear up my

I don't have a pre, but I want to get to the bottom of this. The interwebs is saying that this is enabled by default, not by user prompt. Can you clear up my confusion? It's a propmt when you first turn on the phone? Does the carrier maybe turn it on before sending the phone (for some carriers) causing the confusion?