I am having issues with the same phone as well, but I have made 1 discovery. You need to go to settings and then Data. Slide the data "switch" to ON. This will allow you to text send and receive pictures but unfortunately your phone will keep asking you Sign-in to Network. I am currently try to figure out how to make that stop.
This all stems from not having a data plan, but I think there must be a way around it.