Well my order has been officially cancelled. Walmart's policy and call center reps sucks a$$. They basically do not allow cross-upgrading, and I would have had to pay a tonna money for a phone that I couldn't use. The rep who told me the loophole was supposed to process the order today, but I never received a call. I was then forced to deal with another rep who basically told me that all the information I'd received from the the former rep was wrong. After getting redirected to yet ANOTHER rep who basically told me the same thing, (if the sim is replaced within 181 days, the phone is officially deactivated from walmart's end, and I would have had to pay their Instant Savings Discount price.) I finally just lost it and cancelled the order. I'm now going to order from AT&T. Great price, but it's not worth the hassle. I'd rather deal with AT&T's customer support, who have been far more helpful with this issue.
BUYERS BEWARE, do not cross-upgrade through Walmart.