If i root my htc g2 will it fix the req of the sim network code

Hi , I just get a t-mobile HTC g2 as a gift , and after I factory reset it and I got a problem , I insert a new sim card and it request a sim network code !! And I had sent a message to T-Mobile too but they need me to get the phone owners to contact them to get the code !! If I root the phone and flash a new room , will it Fox my problem ??

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