I purchased a Galaxy s5 outright. It's locked. I don't have a Straight Talk account. I'm starting brand new. Can I take my phone to Walmart, purchase the Straight Talk Activation kit for Galaxy s5 and have the associate get my phone working? The activation kit costs $60. I presume that includes the SIM card I will need for it to work in this phone. Or, do I have to get an AT&T account first in order to unlock the phone so it can be used with Straight Talk? Please be as specific as possible when answering because i am new at this and need all the help I can get! Thank you!