Going to possibly pull the trigger on the "best buy method" to keep unlimited - help me with a couple of details in the steps...

I have unlimited, wife does not. We're both due for upgrades. To keep unlimited for myself I want to go through the steps of the method with you all and make sure its air tight.

1. Upgrade her (non-unlimited) phone line - thus putting it under contract (with the phone I eventually want/will get)

2. wait some time (couple days?)

3. Go online and 'give' my upgrade to her line/phone

4. Go to online source for phones like Best Buy, order phone that she will eventually receive

5. Get new phone in mail (best buy one), put HER sim card in it BEFORE turning it on, put my SIM in the original, first ordered phone.

A couple of questions to clarify some steps

I am a bit lost as to what happens at the step of ordering via bestbuy. If I have given the upgrade to her line (non unlimited), then am I going through the contracting process through/with her information?...even though its under a new 2 year contract originally? Is there any advantage to doing this with the same model phones to not confuse things then or in the future? Does Amazon work as a good alternative as a source for the phone (about the same price for me right now)