I need your help here folks! OK, My wife bought a Samsung Galaxy Y GTS5363 model brand new from Tesco last August on the O2 network but never actually put the O2 simcard in it. Instead she joined giffgaff and put a giffgaff simcard in and it worked fine. She even transfered her number from an Orange simcard that she was using in her old phone., ie the Orange simcard never went into the new phone either. So far so good, the phone worked on giffgaff.
We've recently moved to Australia and thinking an O2 phone would be unlocked to any network tried putting a Telstra simcard in but alas we're getting an "Enter Network Lock Control Key" message when the phone is switched on 
. I contacted O2 thinking they had locked the phone but they say they have no record of the phone on their system and suggested I contact giffgaff as they are the network provider. I'm not sure if it's an agent I need to ask but I thought I'd try on here first so any help would be most grateful.
Try this site:http://www.freeunlocks.com/blog/how-to-unlock-sams