Anthony has a Samsung Galaxy S3 and he can't send pictures via text back to Australia. Leo says that's an MMS issue and he's experienced it as well. He has a hunch that it's a restriction of the carrier. Sending pictures through e-mail should be fine.
Text messages can usually be sent through email this way: @text..com. This sends email to the phone and it'll appear like a text message.
Here's some information from T-Mobile on how to send MMS abroad. Another alternative is to use WhatsApp.