[moko]

i have a att and tmo.....my friend has sprint and i want to buy her a htc tp2(it has both cdma and gsm receivers,so will work on all carriers).....i was thinking the cheapest way is to use my upgrade from one of my 2 carriers,can i hack it to work on sprint....if its possible ofcourse....(she can't upgrade her sprint phone until 2 years)

if its possible.....is this the best/cheapest way.....or should i buy the phone unlocked at full price.

thanks for any help.