OK I seem to have two issues that might be one. i have a Lumia 900. I tried to send a picture via text message and recieved "Can't send message" Try again. I also recieve text message with a picture and it say to "Get media Content" I click on message and nothing happens. I have tried ATT customer service and got no place can anyone help?
Don't know if this will help or not but I found this when looking for the ATT MMS settings for your phone. According to this link, there seems to be a Nokia Network Setup App that was removed from the Marketplace. People that did not buy their phones from ATT, can't get the app and therefore are unable to use MMS.
Not sure if you purchased your phone thru ATT or not but if you did buy from ATT, THEY, of all people, should be able to help with your issue. Good luck..hope you get your phone working.