I am a new customer. We have an iphone 4 on IO6. I have updated the APN using the unlockit.co.nz site. I have updated the MMS settings to use the att.mvno using ibackupbot as described on various places.
I cannot get Group MMS or picture MMS messages to send. They say "not delivered" and "message send failure".
Please advise, this is a huge feature that should work.