Thanks and that is always good to know.
The phone in question is not the unlimited line but one that has 2gb for $30. Mine has the unlimited and I know I can't upgrade directly.
My thought is to transfer my upgrade to her and get a phone, activate and then move her back to her current phone(which is brand new only a month old) then I activate the new one on mine. I also have a couple of dumb phones which are available for upgrade but in great condition and look brand new(in-laws). With these I am thinking transfer upgrade again to my wife's phone buy/activate/deactivate then sell.
My goal is to always have one upgrade available as I would use in place of insurance for a broken device.
So my original question was how long would the phone bought off of transfer have to stay active before I could deactivate and either activate on my line or sell it.