Picked up a second hand iPhone4 with a busted screen, no home button, and missing back plate. I replaced/repaired the thing, got it working again, and used it for a few months, no problemo. This morning, it's in SOS only mode, and after some messing around with the SIM, I checked the IMEI number, which is now blocked. It's locked to Optus, so I called them to try and see about getting in contact with original owner, but they said they don't do that sort of thing. The guy on the phone said I can drop it off to the police but that's it. I'm happy to return it to the original owner, as long as it's not the guy I bought it from. If he's just running some weird scam to sell the phone over and over again, I'd rather not. Any thoughts?