I came across this in another forum
1 go to settings
2 wireless and network
3 mobile networks
4 access point names
5 click menu button
6 reset and You are done
I then switched my phone off and back on again and have received my first picture text :)
did you find a solution to this problem as I am having the same thing happen. I did find a thread that suggested receiving picture texts from iphones could be the problem and that the iPhone had to change its setting.