loading an old sim card into a tMobile samsung gravity2?

[L'amante]

i just got a new samsung gravity 2 today. i put in my old sim card that i have had and my phone shuts on then right back off without even loading the wallpaper then continues to do this constantly until you take out the battery. then sometimes it will turn on for a while but the minute the my faves load it shuts off and on again like before. whats the problem with it? i literally just got it so there is no water damage or damage from dropping it.i even tried the new sim card that came with it but it wont let me call out without talking to a tMobile representative