iPhone using XT/Telecom.
Sending and receiving iMessages via WI-FI works fine. Sending and receiving a pic (or MMS if you prefer) using iMessage does not work unless cellular data is on. There are times when I have moved away from WI-FI coverage and turned on cellular data to find a couple of pics come through on iMessage (usually of my little boy from my wife as she updates me during the day). She has sent them earlier in the day but they have not come through when connected solely via WI-FI
Anyone got an idea about a remedy on this?