You dont need to root you just need to get the new carriers prl on the phone, which can be done thru epst (##778#) on a stock sense rom. This works for cricket, boost, page+, etc. But major carriers (vzw sprint at&t) will not accept phones on their network that they did not sell you. In that case you need qpst and cdma workshop to clone a good esn from a phone on that carrier to your phone (which is illegal by the way). Sometimes on these networks it is hard to get data and mms to work, that is where root comes in.I didnt know when it was posted. Though why does every1 say you have to root phones to flash to carriers when you can get everything working on stock rom. what 3 years ago they didnt know the command ##prl# or was that in updated stock rom? or ##778# or ##program# these phones dont need qpst dfs or cdma workshop to flsh to cricket page plus only carriers that need nv files.
Somehow along the way switching to other major carriers got jumbled in with switching to other smaller carriers, even though the process is very different.