A:AnswerIf you buy the SIM card from Best buy then I would say that they would help you with the transfer of service from the old phone to the new phone. You asked if you have to buy the subscription and what does it provide... By the word subscription, are you referring to the monthly plan? The monthly plan is going to be dependent on which carrier you choose. For example which plan you choose on AT&T won't exactly the same and features offered as well as price with another carrier.
