A:Answer The SIM card is a separate purchase from the pre-paid unlimited data plan. You'll have to purchase one month of the pre-paid unlimited data plan of your choice (upon installing the SIM) to get things started. Plans change, so I suggest checking out the latest offerings at: https://www.att.com/prepaid/plans.html Also, be sure to read the footnotes in the chart at that web site.
The folks at Best Buy set things up for me for one of the pre-paid plans when I purchased a new smartphone. The one-month pre-paid fee was charged to my credit card.