SMS doesn't support pictures at all. MMS is layered on top, where a hidden sms is received telling the phone to fetch the media via http. That is why you can r

SMS doesn't support pictures at all. MMS is layered on top, where a hidden sms is received telling the phone to fetch the media via http. That is why you can receive text messages without data, but not pictures. I don't know the details of the MMS spec, but I know the mms picture quality improved when I switched carriers several years ago.