are you running on att or unlocked to a different network. if you are on att then it will not work unless you have mms on you account which you dont because att didnt give any iphone buyer mms. but if you call them and convince them that you no longer have an iphone and want to add mms to your account then swirlymms will work wence you put in the correct numbers from
http://www.swirlyspace.com/iphone/ap.../settings.html