Cellular Data not showing on iPad 3


    Purchased new t-mobile sim card to put into an older iPad 3 and the previous sim card was moved to a new iPad Air.  If I turn off wifi, cellular data does not work.  Does the new sim card need to be activated?  I thought it would have been activated at the t-mobile store when I bought it.  I do see the SIM card number in IPAD but no phone number is listed (I know the phone number by looking at t-mobile acct). 

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