To check your memory usage please go to Settings> Applications> Manage applications' bottom left of your phones screen it will display internal storage used on the right side of the screen free memory will be displayed. Please note that you can install MicroSD up to a maximum of 16GB on this phone.
You can move some apps to your SD card to create more internal free space, to do that' touch the app you want to move and then touch "Move to SD card". Please note that not all the apps have this options.
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