buying new iphone from third party?

There is no publicly accessible, reliable IMEI database anywhere on the internet. Such a thing does not exist as neither manufacturers nor carriers provide that data to any web site or developer. Similarly, there is no local, national nor international stolen device database, so there is nowhere to look up or confirm a device is stolen or not.

When you buy a used iphone from a private party it quite literally is a situation of taking your chances. Especially if you do so without physically meeting the seller, and physically inspecting and checking the device yourself (e.g. is it truly carrier unlocked?, is activation lock actually disabled?, has the device truly been wiped back to factory init. state?, is it blacklisted with any carrier or nationally (in the USA, blacklisting is universal)?, etc).

There is no way to reliably verify many of those important things before buying, especially if buying from an anonymous person online. So private party sales are always a situation of caveat emptor (pay your money and take your chances).

Personally, for an expensive device I rely on daily, the risk of saving a few bucks to buy used in a private party sale has never made sense to me. These forums alone are rife with stories of people doing so, only to end up out of pocket for the money, and with no useable device in hand (and no way to rectify the situation).

Everything Michael said above.

Plus, the seller can (and has been known to) report the phone lost or stolen days or weeks down the road for insurance fraud, in which case, it will be blacklisted at that time. Just because it works today is no guarantee. Know your seller or know a sure fire way to contact them down the road if there is a problem.

You’re welcome Jon. There are just so many sad stories of people getting ripped off in one way or another here every week that I think it is best, IMO, to avoid buying used. An exception of course could be someone you know well, do indeed trust and where you can make the transaction face to face and know they will let you check it thoroughly beforehand, and they’ll do the right thing and help if an issue comes up.

There are some decent places to buy used. Some carriers sell used, and you can then go back to them if there is an issue. Amazon itself does not sell new iPhones at all, but they do sell Amazon Refurbished used iPhones, so you at least have an Amazon satisfiaction sales guarantee and whatever their refurb partner’s offer in terms of a warranty on the device. Apple itself sells OEM refurbished iphones online, and those come with a full Apple warranty and are eligible for AppleCare+.

But none of those will have iPhone X models available this early in the device life cycle (right now Apple only has refurb iPhone 6s and 6s+).

Why? The iPhone X is still in high demand. Anyone offering to sell one for anything significantly less than retail should be suspect. That's not normal.

Buy a new one from an authorized source.