Open settings then under Xperia connectivity tap More then at the bottom open Internet settings then Accept - A list should appear with networks on it - Now make sure to select the right network - Some may have two, One for PAYG and the other Contract - These have different settings to make sure to select the right one for you - Once selected you should be able to send and recieve MMS and use Mobile data - If you are a PAYG customer then check you have a data plan allowing you to download the content as these do not use wi-fi
