19. From the Home Screen, tap Messages
20. send a picture message to a friend
21. Ask the friend to verify they received the picture message
22. Ask the friend to send you an MMS picture message
23. Make sure you received the MMS picture message.
Once you are done, place your T-Mobile SIM in a safe place. If you update iOS on your phone, you may need to repeat these steps.
If you had problems, check the FAQ
Did you try the guide? Leave a comment and tell me if it worked or what went wrong!