How to block (send n receive) picture messages iPhone 4S

How can I block picture messaging on my iPhone 4S (sending and receiving) I'm currently with Fido, do I have to call customer service or is there a way on my phone? I saw this MMS messaging thing, but I'm not sure what that does exactly if I turned it off. If anyone knows how to turn it off directly by doing it on the phone itself, please let me know, thanks!