Apple-unlocked iPhone became locked suddenly!!
I have an Apple-unlocked iPhone 3GS which I bought in Australia 2 years ago. It's always worked fine with various SIMs and varuious carriers - I travel a lot so unlocked was my chocie as I use SIMs in each country I visit. Recently in UK, I bought and installed a prepaid (pay as you go) SIM while I was there and now I find the phone is locked to that carrier. Well, at least it will not make calls - it'll recieve calls and it'll send and recieve SMS messages, but I can't make any calls - it just begins the calling process then gives call failed message. Now I find the problem, I've moved on to another country so getting the carrier to see to it is impossible for me. So now I have a locked phone because somehow a carrier has been able to disable the factory unlock by using their SIM I installed. This is a carrier I have not used before with this phone.
Amazing... how can that happen? How can a carrier have that sort of power over the device???
Can anyone tell me what's happened here? How can I get back to the original unlocked state?
I've tried a total Restore, but no change - still locked.
Thank you in advance for any help offered.
MacBook Pro 3.02 GHz, 15, Mac OS X (10.6.8), 8GB RAM, 3 iPods, iPhone 3GS, iPad