I have ported my number from Orange to T-Mobile and the phone is working with my old number but still displays the old T-Mobile number on iTunes, Contacts and Settings>Phone.

Is this taken from the SIM card and not the network so will always be wrong?

Of course it is taken from the sim card. How would itunes contact every network to find your phone number?

Well it said N/A when the sim was in before but not unlocked.

Do you think Itunes is looking at every network in the world to find out what your phone number is? And exactly what information would it use for this search? Of course you also have an unlocked phone.

Its quite possible the phone would retrieve its number from the network on first connection and store it temporarily in the memory so it displays the right number and passes it onto itunes when put in the cradle.

Vodaphone provide this when you enter *#100#

AT&T users must have the same problem. Maybe AT&T send out a new Sim to all customers who swap numbers?

Thanks for your help.