How did an Iphone that didn't have a passcode, get locked?

An elderly friends iphone all of a sudden is locked and it says "disabled, connect to itunes" but she didn't have a passcode on it and all she can do is emergency call and it will receive calls but she can't call out.

I can't tell you how it got that way, but when it's locked you out for too many passcode fails the only recourse is to erase and recover it. Hopefully she's got a fresh backup or is synced up with iCloud.