Currently Being ModeratedApr 23, 2013 10:20 AM (in response to benja303)
Then you did not purchase an unlocked phone.
No one but Apple can tell you whether the phone is locked or to which carrier. Talk to whoever you bought it from or call AppleCare, give them the serial number, and find out who it's locked to. ONLY the carrier it's locked to can authorize unlocking it.
Currently Being ModeratedApr 23, 2013 11:01 AM (in response to benja303)
While Kilted Tim is correct you should be able to view the carrier in settings > general > about if you can get to those screen (not in ios setup) if not then Kilted Tim is absolutely correct. Call Apple give them your serial number and they will tell you whether it is unlocked and if not who it is locked to. After which you should contact that carrier to get it unlocked.
Currently Being ModeratedApr 23, 2013 11:10 AM (in response to benja303)
I bought an Unlocked Iphone from somebody and it is Factory unloicked but it says " SIm not valid"
I have verfied that is indeed unlocked by usuing an internet check, i can't remember the details of the check but it had me type in my model number i believe. And it says the Iphone is unlocked.
There is no "interent check" that can tell you whether your phone is locked or unlocked. The sites that claim to do this are all scams. Only Apple can tell you the lock status. But your symptom says that your phone is locked to some carrier.