iMessage photo messages not working?

I have an iPhone 4 on iOs 6.1.2 through Net10, for about the past two weeks I haven't been able to send photo messages throught iMessage, well they say they were "Delivered" but my friend in the uk hasn't received them (it worked previously and they send fine through my iPod touch.) I've toggled imessage off and on, rebooted, reset my network settings, messed around with the apn settings (for 3 hours) sending myself a photo from my iPods to my iphone works but sending it from my iphone to my iPod doesn't work. Does anyone have a fix for this or having the same issue?