That might be the problem (no data plan) , although I do believe you can send/receive mms w/ simpler phones (25c per) , so you should be able to as well .
I was getting red x's . Called Cing... they led me here .
https://www.wireless.att.com/support...orialId=389120
If that's not correct , go thru support . Choose phone . Then choose "Go To Tutorials" .
2. Select Catagory (choose Picture Messaging)
3. Select Tutorial (choose configure MMS settings)
If I would have known that I could've done it myself . It worked when I unchecked the appropriate boxes .