My iPhone is locked what do I do?

My friends iPhone is locked in lock screen. And the slider to unlock it says " slide for emergency " and if I slide it a keypad appears for an emergency call. And the background is a picture of a charger and the iTunes symbol so what can I do to unlock it. By the way it's black and it looks like an older version, curved bottom very thick, heavy iPhone.

Hook it up to iTunes.

Turn it off and on again, unplug it from charger too.

If it carries on, take it to the network provider or apple store and get it fixed. Might just need new software update in which case you plug your phone in to a laptop or computer and download the software onto the phone- free of charge.

Put an AT&T SIM card inside.

It's a 3G.

Watch and be amazed.

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