Tmobile contract sim card in tmobile prepaid phone?

I'm planing on buying a tmobile prepaid phone and I wanted to know if I can use my tmobile contract sim card on the tmobile prepaid phone

If the phone is not locked with a different country T-mobile network, then you can swap network. If not, I suggest you can approach Unlocking4free.com and specify the country,locked network of phone.Based on the availability you can get the permanent unlock service along with free instructions.