How can I check if the SMS is stored on the SIM card?

Question

I am using a cursor to loop through the SMS in my phone, like this..:

Uri uri = Uri.parse("content://sms");

Cursor c = getContentResolver().query(uri, null, null, null, null);

while (c.moveToNext())
........

How can I check if the current SMS, when I am looping using the cursor, is stored om my SIM card or not? Can't find a way to do this but clearly there is a way, since the included Google Message app can show the messages stored on the SIM card....?

Regards,

BTJ