How to check iPhone authenticity

Did you already purchase this iPhone? Or are you thinking about purchasing from someone other than Apple or one of the Apple certified retailers?

I'm copying the information from a very good user tip developed by one of the Apple community specialists. Thanks lobsterghost1.

The All Too Common SAD Reality of Buying … - Apple Community

The Pre-Purchase Checklist:

1. Don't buy any used iOS based device from an individual you don't know and can't validate the device has not had Activation Lock removed. NEVER EVER EVER EVER!
2. If you can't see the device in person, move along.
3. Make sure the device can accept your Apple ID so you can actually set up the device.
4. Ask for the Original Purchase Receipt for any used device (you may truly need this in the future). The receipt should show the device serial number on it. If they don't have it or won't provide it, move along.
5. If you can see the device in person ask the seller to turn it on for you. If it doesn't open to the Hello Page or pairing page for Apple Watch, get up and move along.
6. Never invite someone to your home you don't know or haven't met to purchase a device from.
7. Only meet someone in a public location where other people are, preferably at a Police Station. Many cities have local Police Stations where a safe spot for transactions like this can be made. If the seller is unwilling to meet at a Police Station, that should be red flag enough. Move on.
8. Don't agree to meet someone in a parking lot. EVER. Recently a person trying to sell their iPhone not only didn't sell their phone, they were held up at gunpoint and their BMW hijacked. Is it really worth the risk of meeting someone you don't know, in an unsafe location where they could rob you or worse?
9. If you are still intent on buying the used device and you have heeded all the above advice, CHECK THE DEVICE OUT carefully. Make sure the power button works. Make sure the volume and all buttons are functional. Make sure the screen responds to your touch. Make sure the device isn't bent, or dented.
10. Ask to see the sellers ID, like a drivers license and make sure you can call them and have their email address. Validate their contact information before leaving with your new iPhone/iPad/Apple Watch
11. Again, if it DOESN'T OPEN TO THE HELLO PAGE, OR SET UP PAGE FOR APPLE WATCH, WALK AWAY. An iPad of iPhone which has been prepared properly for a new user will ALWAYS open to the HELLO PAGE when turned on, followed by setting the language and then the set up assistant will walk you through connecting to a Wifi Network, following all the way through setting up the iPhone/iPad as your own. An Apple Watch, which has been prepare properly for a new user, will tell you to place the watch near your iPhone to start the pairing process. If it doesn't, you can't use it.

The Post Purchase SAD REALITIES:

1. Without the Apple ID and Password from the previous owner, no Activation Locked iOS device can be bypassed by you. Period. Don't come here asking how. It can't be done. The FBI couldn't do it. And if they couldn't the chances of you doing it are Zero - Zip - Nadda.
2. Do NOT call Apple or go to an Apple Store and ask them to unlock the device. Apple will NOT help you unless you have the Original Purchase Receipt with the Serial Number of the device plainly printed on it.
3. If you can't locate (on your own, no one can help you) the previous owner of the device, understand your device is useless to you or anyone else. Only they can unlock the device.
4. Do not try to find a 3rd party service who claims they can bypass Activation Lock. They can't. Remember, the FBI couldn't bypass Activation Lock and they most assuredly have far better technology than some little 3rd party service. Sure, they'll gladly let you pay them a fee to try. But they CANNOT BYPASS ACTIVATION LOCK. So don't throw more money away.
5. The first thing you should try to do is return the device for refund. If you read what I wrote above however, many less than honest people sell stolen goods. There's a good chance you won't be able to reach them ever again. If you can however get your money back, that's great. Chances are you can't and you are now stuck with a completely useless device.

Where did you buy it from?

The All Too Common SAD Reality of Buying … - Apple Community