For those of you who want to SIM unlock your T-Mobile smartphones, there is an easy way to do it using T-Mobile’s Device Unlock App. Now, the Device Unlock App only works if you have paid off your EIP in full(you have to pay off your installment plan). As soon as you pay off your EIP, you can unlock SIM right away and in this SIM unlock tutorial I paid for my EIP and was able unlock SIM within 5 minutes of paying off EIP. Also, if you have paid full for your device you can easily unlock SIM. Yes, this 100% FREE.