Originally Posted by mogelijk
That is just a prepaid card to add $30 to your T-Mobile account. It isn't needed for the $30/month plan.
What you will need is a T-Mobile Monthly SIM Kit. The cheapest place to get that is from the T-Mobile website
, though you can also get them from T-Mobile stores (typically are around $10 in the store). Once you have the card and are ready to activate, just activate online and have a method ready to add money to your T-Mobile account (prepaid card or credit card).
I did reread your original reply, but I'm still unclear on where
online you activate. Is that apparent after receiving the SIM you linked to? Thank for indicating the cheapest way to order it, and all your help, by the way.