First of all, call your carrier and ask nicely, if your contract has expired, they'll hopefully unlock your phone for you.
If you tell your carrier you'll be travelling and wish to use
a SIM card from another country to save on roaming fees, they may also unlock your phone for you.
The carrier might not want to unlock your phone. Each have rules about who is 'qualified' to get an unlock code, and if you're still under any sort of finance contract for the phone, they may not want to give you one. While these rules are different from carrier to carrier, generally you'll have to have an account in good standing, have had the phone for a certain period of time, and what they consider a good reason for network unlocking your phone.
You can also unlock screen code and sim-card of T-mobile myTouch 4G Slide mobile phone. But you need to do first unlock code for it's operating system.
If the unlocking code is not working for T-mobile myTouch 4G Slide, you need to enter your phone IMEI number to the box to get new one.
All codes are generated by us.