Q: Hello,

YOu will need to contact O2 and see if they will unlock the phone for you.  ONly the carrier that the phone is locked to can unlock it.

Carphone warehouse does NOT sell unlocked phones.  The phones they sell will only activate with a UK carrier and will lock to the first carrier used.

The ONLY source for unlocked iPhones in the UK is Apple.

From reading other post re: car phone warehouse - your phone is locked, if it wasn't your mum wouldn't have any issue with using a different sim card.

Car phone warehouse ISN"T an authorized Apple dealer. 

razmee209 wrote:

Car phone warehouse ISN"T an authorized Apple dealer.

Actually, they are. They are authorized agents for the carriers in the UK (just like Best Buy is in the US). But unlike in the US, the phones are not locked out of the box. They will not activate, though, with a non UK carrier, and they will become locked to the first supported UK carrier SIM used.

They don't seem to be very honest, but they are authorized to sell the iPhone.

It is locked. What you describe is a symptom of it being locked, and, as you have been told several times, a phone from Carphone Warehouse can only be used with a UK carrier, and will become locked the first time it is used.