Activation help

If you are trying to activate an iPhone and it is asking for a previous owners Apple ID and password, you have encountered the Activation Lock. This is a security feature that prevents thieves from setting up and using a stolen or lost iPhone. You have no alternative. You must contact the previous owner to get permission to use the device. If you cannot contact the previous owner return the device to where you bought it and demand a refund. You will never be able to activate the device and no one can help you do it.

You can't. The activation lock is an anti-theft measure.

If you bought it through a place such as eBay, ask the people running the site or store for a refund.

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Doesn't matter where you bought it.

It means you can't use it until you have the ID and passcode of that last user.

Sounds to me like you may have bought a stolen device.

Turn it over to the police. The phone is probably stolen.