said by MGK645:I just did this yesterday - still works. Part of the trick is to make sure you activate the new smartphone on the new line, then switch it to your unlimited line - may require a new SIM card though.
Say you get a GS5 so that's $200, activation fee $35, extra line of service for 24 months $10 plus taxes and see so at least $13-$15. Total=$350-$400 total=$550-$600. Just buy the damned phone.