If you want to migrate to T-Mobile, now you can do it for free, without the necessity to pay activation fees. Their prepaid SIM card kits usually sell for $10, but if you enter “NOVSIM” as a coupon code at the checkout stage, a person can get up to two SIM card kits for free. All you have to do is head to the T-Mobile site (use the source link at the bottom of the article), choose your preferred type of SIM-card, and voila - you're done.
Once it arrives via mail, you are ready to choose a plan and activate the SIM card. By the way shipping is free, too. There is a chance that you will experience the following error while trying to checkout:
“Sorry. We're having some problems with your order. It looks like our Payment Processor couldn't be reached or might be down. Please try again or contact us so we may assist you with this order.“
If this happens to you, it is recommended to either try checking out again or call the provided phone number.