That depends on your device. If you have a GSM device you will need to purchase a Pix World Sim card from Pix at PixWireless.com/SIM.
If you have a Sprint Device, you will need a SIM Card for LTE connectivity. The good news is your device probably already has one in it. During the Activation process, we will gather that info.
If you are missing the sim, they may be purchaed from Sprint directly.
Not sure what kind of device you have? Check your device here for free