Guys.....some phones are just not able to play nor receive the files. I could tell you a lot more if you'd inform us of the type of phones you have.
From what I have found out, basically if your phone has both video and a camera on it, you can receive the files, if not, well then, it's touch and go.
And also as mentioned, there are file sizes depending on the type of phone. For instance, the LG 6000 is limitied to 30k while the 7000 and 8000 have ranges from 100 to 200k.