How to Read SMS Messages on an SD Card
In most cell phones, text messages are saved on the phone memory or the SIM card memory. However, if your cell phone comes with a microSD card you can switch the default memory for storing text messages from phone memory to the microSD card. This is useful if you're running short of free phone memory and want to store a larger amount of text messages in your cell phone folders.
Press the "Menu" button on your phone.
Go to "Messages" or "Messaging." Specific instructions might vary from cell phone to cell phone.
Press the "Options" key and select "Settings." In the "Settings" folder, select "Other."
Specify "Memory in use" as "Memory card." This will let you read SMS messages stored on your memory card.