why cant my new tmobiile chip work in my phone [ samsung u600] and my 02 one can?

[mixedgirl:t]

when i put it in it seys invalid sim ?

iv jst gotten it 2day

[Mrithika]

Your Samsung U600 has been restricted to O2 network. That is why it is not working with Tmobile network. It wont even work with any other network unless the network restriction is removed. To remove the network restriction you need to enter its unique unlock code. You can get the unique unlock code for a Samsung U600 from Unlocking4U.Com at affordable cost with easy unlocking guide. Good luck.