The SIM card enables transmission between a wireless or mobile network and the Android device. The method of inserting a SIM card into your Android device will vary depending on the location of the SIM card slot, whether it is under the battery or in a SIM card slot.
Steps
Method 1 of 2: Insert a SIM card into the battery slot

Step 1. Make sure your Android is turned off

Step 2. Remove the battery cover from your phone
In most cases, you can do this using your fingertips.

Step 3. Lift and remove the battery from your Android device

Step 4. Insert the SIM card into your device
Be sure to respect the direction as shown on the thumbnail and paying attention that the golden part is down.

Step 5. Place the battery in the battery compartment

Step 6. Replace the battery cover
Your SIM card is now inserted and ready to be used.
Method 2 of 2: Insert a SIM card using the SIM card slot

Step 1. Make sure your Android is turned off

Step 2. Find the SIM card slot
It is usually found on the side of your device.

Step 3. Use the SIM card puller
Insert it into the small hole that is next to the SIM card slot. In most cases, the device manufacturer will provide you with a SIM card extraction key along with your device.

Step 4. Gently pull out the SIM card slot
Use your fingers once it is accessible.

Step 5. Put the SIM card in place
Place your SIM card precisely and carefully into the slot so that it fits properly.

Step 6. Complete the operation
Push the SIM card slot gently until you hear a clicking sound. So your SIM card will be ready for use.