Is anot a very popular media container format designed for mobile phones; works with standard CDMA2000. The main difference from other media containers, 3GP, is the lack of support for AAC format audio tracks.
This format was originally created as an alternative to mp3. The idea was to achieve a small file size with better sound quality. The first versions weren’t quite successful, but with the development of AAC, it became possible to store sound with less loss of quality, and with the same file sizes as that of mp3.