Converting .h264 videos to .3g2 format.
Converting H.264 Encoded Video Files directly to 3GPP2 Multimedia Files (.h264 to .3g2 conversion) should be possible and quite straightforward.
Use a video editing program or (online) conversion tool, such as the Adapter or FFmpeg, which should allow users to import H264 videos and re-save them in 3G2 format.