You treat files like any other stream (such as Serial). You open the file, then you read from it into a string (usually a character at a time) parsing it as you go. Then you can send that string elsewhere, such as to your GSM module.
You treat files like any other stream (such as Serial). You open the file, then you read from it into a string (usually a character at a time) parsing it as you go. Then you can send that string elsewhere, such as to your GSM module.