Article: If you use your J7 on either T-Mobile or MetroPCS, you may be able to unlock your phone by running an app that's already installed on your device. See Unlocking a Samsung J7 on T-Mobile or Unlocking a Samsung J7 on MetroPCS before proceeding with this method. There are 2 different ways to get an unlock code, and both require having this 15-16 digit ID. Tap the Phone app on your device to launch the phone keypad. Dial *#06# The number will display on the screen as soon as you enter the last # sign. Write this down so it's available. You can also find the IMEI in the Settings apptap "Status" and then scroll down to "IMEI." As long as your account is in good standing and you own your phone outright, your network provider should give you an unlock code without issue. When you call or chat with your provider, be ready to provide the IMEI. If you aren't able to get the lock code from your provider, you can pay an unlocking service to generate a code. These codes usually cost about $20, and can take around 24 hours to arrive in your email inbox. When choosing an unlocking service (there are many!), make sure it meets all the following criteria: Has a customer service phone number. Does NOT require you to install any software/apps. Has a refund policy if the code does not work. Has a legitimate website and a good reputation. You won't need to enter the unlock code until you've installed a SIM card from another provider. When you are ready to use your phone on your new network: Hold down the power button on your J7 and select "Power Off." Turn the phone over so you are looking at the back. Notice that there is a small divot at the top left of the phonethat's there to help you remove the back cover. Insert your fingernail into the divot and pull the cover gently away from the phone. You will see two card slots just above the batterythe SIM card is in the slot on the left side. Remove the battery: Insert your fingernail into the divot at the bottom right corner of the battery, then pull it outward. Gently slide the SIM card down until it's completely out of the metal holder. Put it aside. Slide the new SIM card into the slot, gold side facing down. Replace the battery and back cover. Press the power button to start your phone. You should see a message that says something like "Enter Unlock Code" or "SIM Network Unlock Pin." When the unlock code is accepted, you'll see a message that says "Network unlock successful." Once your phone is successfully unlocked, you'll be able to use it on your new network. If you see "Network Locked" and nowhere to enter an unlock code, dial #7465625*638*# (in the phone app) and then enter the unlock code when prompted.

What is a summary?
Try using the Device Unlock app. Write down the IMEI number for your phone. Ask your cellular provider for the unlock code. Pay for an unlock code. Insert your new provider's SIM card. Power on the phone. Enter your unlock code.