How to buy a used iPhone; what to check?

Now that the iPhone 15s have been out for a few weeks, I’m probably going to be switching from my current iPhone 7 Plus to a used 12 or 13 Pro Max. Most likely off of Craigslist, NextDoor or Facebook Marketplace.

As it has been a long time since I’ve done this, what are the things I need to check (and how to do it) to ensure that the iPhone I purchase is fully unlocked to carrier, unlocked to iCloud, has a clean IMEI and most importantly, the one or two or three other things I don’t even know about?

Of course, the normal precautions for meeting strangers with large amounts of cash in my pocket apply.

It is my understanding that the 12s and 13s use the same nano SIM as the 7 Plus, so putting my SIM into the prospective new iPhone should show that it will connect to my carrier (Consumer Cellular - AT&T flavor). If this happens, does it mean the iphone is fully carrier unlocked?

Should I ask the seller to perform a factory reset of the iPhone? If they are able to do so, does that mean the iPhone is fully cleared of everything important and it can easily become my iPhone after restoration from my iPhone 7 Plus backup?

Thanks for your time and advice.

Maybe. Some here have said that it works. But some carriers say that if you do this, you may not get access to the latest and greatest network features (e.g. 5G).

If it works for you, but some things don’t seem quite right, or if you just want to be extra careful, you can contact Consumer Cellular and get an updated SIM card for the new phone.

I would assume so.

The critical thing is to make sure “Find my iPhone” is disabled. If it isn’t, then it is still tied to the previous owner’s Apple ID and you will not be able to break that association without his iCloud login credentials.

If Find My iPhone is not disabled and the seller can’t disable it for you, then you should assume the phone is stolen and cancel the deal.

If it is disabled, then you can (and should) factory reset it yourself before you install your SIM card or migrate any data to it.


Have a look at battery Condition in Settings > Battery > Battery health and charging > Maximum Capacity. A new phone will have 100%. My two year old iPhone 13 Pro Max is at 88%. Apple threshold for replacement is 80%. Low health is not a reason not to buy as battery can be replaced for about £70 but should be factored into price.