My old t-mobile smartphone was easy to activate from their site. Just need activation code, sim card serial #, and phone serial #. Activation code and sim card serial # will already be in the sim card package you buy. phone serial is in the back behind battery of the tmobile phone. Dont really remember how long it took, maybe 10-15 min to activate. But the phone itself might take hours to receive the activation, which could be annoying.