I buy a non-activate iPhone 15, but the model number starts with 5. What does it mean?

If you mean to say that you purchased an iPhone that is activation locked, you will not be able to use it. The original owner will have to unlock it for you. If that is not possible, ask for a refund. As for the model number, you can type the whole model in google to identify the model. But as I said, knowing that will not unlock the phone so you can use it.

The phone that you purchased was used and refurbished by a third party company not approved by Apple. As such, it may have non-genuine parts........a poor quality battery, screen, etc.

If by "non-activate", you mean that the phone has not been set up for service with a cellular carrier, you will need to contact a carrier to see if you can set up the phone with them.

If "non-activate" really means that there is an Activation Locked message on the screen, you will not be able to use the phone at all. Return the phone for a refund.

Karonack7 wrote:

Thank you for the reply. By what you said, it is not a non-activate phone. I can use it. Just the model number is strange, starting by number.

Bob Timmons, is correct. The phone you bought has been refurbished, NOT by Apple. If you thought you were buying a new iPhone, you didn't. But that's a discussion you'd need to have with the seller. Apple is not a party in your purchase and there likely is no warranty provided by Apple on the phone you purchased.

The phone that you purchased was used and refurbished by a third party company not approved by Apple. As such, it may have non-genuine parts........a poor quality battery, screen, etc.