My Ip4s is on Orange. It is not roaming on T-Mobile. However if I type in *3001#12345# on the keypad it displays T-mobile. Can anyone else try this and see if they get anything ?

i type it in, on my 4S and i get nothing come up. (Also on Orange)

Did you press the call key or just type it in? I just typed it to the keypad and it then displayed T-Mobile.