Short answer: before you pay, make sure Activation Lock is off — Apple says plainly not to buy an iPhone with it on — then check battery health, that the model runs current iOS (iPhone 11 or newer is the sensible floor), the screen and ports work, there is no swelling, and the phone isn't reported lost. On arrival, erase it, update it, and test it on your Mac before it joins the rack.
Before you pay
Apple's guidance for buying a preowned iPhone, checked 17 September 2026 (Apple Support):
- If the phone shows a lock screen or passcode, ask the seller to erase it so you can test it.
- If it shows the Hello screen, it has been erased; you'll need to set it up and activate it to test it.
- If Activation Lock is on, ask the seller to enter their password to turn it off. Apple's words: "Don't buy an iPhone if Activation Lock is enabled."
Buying in bulk from a reseller? Ask in writing that every unit is erased, Activation Lock off, and returnable if not.
The checklist
| Check | How | Pass |
|---|---|---|
| Activation Lock | Set it up; it shouldn't ask for someone else's Apple Account | Off |
| Model | Settings → General → About | iPhone 11 or newer (see which iPhone) |
| iOS support | Model can install current iOS | Yes |
| Battery health | Settings → Battery → Battery Health (or Battery Health & Charging) | Your threshold; see below |
| Swelling | Screen and back sit flat, no gaps | No lifting at all |
| Screen | Full white and dark images; touch across the whole screen | No dead zones |
| Charging port | Charges and shows on a Mac with a data cable | Both work |
| Buttons | Side, volume | All respond |
| Wi-Fi | Joins your network, loads video | Yes |
| Carrier lock | Only matters if you'll use SIMs | Unlocked if needed |
| Parts history | Settings → General → About, look for parts notices | Understood |
| Storage | Settings → General → About | 64 GB or more |
| Managed profile | Settings → General → VPN & Device Management | None |
Battery health: what the number means
Apple says batteries in iPhone 14 models and earlier are designed to retain 80% of their original capacity at 500 complete charge cycles, and iPhone 15 models and later at 1000 cycles, under ideal conditions (Apple Support).
Farm phones stay plugged in with the screen on, so a phone already near 80% will need a battery sooner. Set a threshold you're comfortable with, price a battery swap into anything below it, and see battery care.
Red flags
- The seller won't erase it or turn off Activation Lock.
- A managed-device profile you can't remove.
- A lifting screen or back — that's a swelling battery; don't buy it.
- A price far below similar listings with no explanation.
- Mixed models sold as one lot when you asked for one model.
On arrival
- Erase and set up as new.
- Update to current iOS.
- Run through the checklist again.
- Connect to the Mac with a data cable, trust it, and confirm it appears.
- Label it and add a row to your inventory sheet, including where and when you bought it.
- Run it on its own for a day before it joins the rack.
With Farmero
Farmero needs iOS 17 or newer and drives phones over USB. Once a used phone passes the checklist, the per-phone setup — runner install, Developer Mode, Auto-Lock — is in the Mac setup guide. The cost side is in the cost breakdown.
FAQ
What should I check first on a used iPhone?
Activation Lock. Apple says not to buy an iPhone with Activation Lock enabled.
What battery health is acceptable for a phone farm?
Pick your own threshold. Apple designs iPhone 14 and earlier to keep 80% at 500 cycles, and iPhone 15 and later at 1000. Farm use wears batteries faster, so budget a battery for lower readings.
Does carrier lock matter?
Only if you plan to use SIM cards. On Wi-Fi it doesn't matter.
Is it worth buying the same model in bulk?
Usually. One model means one set of stands, one set of settings, and faults that are easier to compare.