I'm wondering if you could get a top-of-the-line iPhone from the sort of place that has month-to-month prepaid contracts with no names or credit card numbers asked? I've had a few of those deals when I was home on vacation, but the phones were all no-name Chinese models stuffed to capacity with adware and bloat. My MC is magically compelled to get (currently an iPhone X, subject to update as long as it takes me to write this) with unlimited data and calling, but I think the antagonist forgot to specify how long the phone had to work for. If so, he might be able to exploit the contract (he's kind of a stand-in for the Devil at this point) such that the antag thought she got what she wanted, only to find out a month later that she'd been snookered. Just, do those sorts of places (the bad ones) sell those sorts of phones (the good ones)?
Given the supernatural leanings of the story, I'd say that the data plan and update-ability of a hot iPhone will rank fairly low on the suspension of disbelief meter.
