Nope. Just swap the sim cards between phones or if you're switching to a different sized sim card, login to self-serve to swap your sim card (go to change phone, and choose new sim card option). Same if you're switching from a BB with no sim card to a sim card device.
If your phone is unlocked,you can simply swap your sim card in it.. If not get your phone unlocked either from your Sp or any third party vendors online like http://www.wickedunlock.com . the plans will remain the same as it is in your previous phone