A month ago, I picked up a used AT&T HTC One. I got service thru straight talk and everything worked EXCEPT MMS. I tried every APN I could find, to no avail. Now I've switched to H2O wireless and have the same issue. Spent hours on chat and await a call from tech support, but I forsee the same outcome. Are there any other settings that could have been inadvertently changed to prevent MMS from working?? Any help would be much appreciated!