Flashed Rataplan Lumia 710

[lchan51]

I unlocked and flashed a Rataplan ROM to my Lumia 710. The phone is also SIM unlocked. In the phone calling tile it is displaying US and not T-Mobile as it should/used to. Also, when I scan for available carriers my choice also show up as "US" or "AT&T". I have inserted a Lycamobile SIM and it correctly displays as Lycamobile on the tile. Does anyone know how I can get T-mobile to display instead of the generic US? The interesting part is that I have flashed these ROMs onto another of the same phone and it displayed correctly. It is not a SIM problem. Any suggestions?