In the US and Canada, as far has I heard are working toward, the unlocked phone ideas, getting away from, those binding contracts so that, you can switch carriers, Soon you will be able to unlock and use the carrier you desire.. or pay in advance the minutes you think you'll use per month!
But note, if you have and outstanding contract, you may have to pay a penalty if you switch carriers. or wait till the contact ends!
The good part is, that you will be able to buy or like in the case of unlocked Droid, Windoz phone and a sim card, to get you up and going!
At home you can use your wireless net, or allot of public place offer free wireless to their customers, so you can, do home work on the run or at home and, just use you phone with the hours you buy!
There are places that sell unlocked phones already, so before you jump on board with and binding contract, shop around!