if ur previous phone used a ruim, all u need to do is put that ruim in any android cdma phone and see the MIN number in the settings.
to reprogram the phone, dont bother with all the commcenter stuff, just go to www.cdmatool.com, pay $10 and use DFS to reprogram your ip4 - its a much cleaner and hassle free process.
but before you program your iphone, make sure that you get EVDO internet stopped on your old phone otherwise you will be stuck with 1x on your iphone. Pester the reliance store ppl to stop your evdo.