Match the phone, not just the extension
A .3gp filename alone does not guarantee playback. The device also needs to support the video's dimensions, codec, frame rate and audio. Check its requirements first; if it accepts MP4, that may be the more useful format for your clip.
Make a small compatibility sample
- Drag the AVI file into OneClick Video Switch. Open Edit and Trim if you want to test only a short part first.
- Search for 3GP in Find format or device, then choose the 3GP preset that matches the target device, such as 176x144.
- Review the queued output dimensions. Use the selected 3GP dimensions rather than leaving an arbitrary source size unchanged.
- Choose a destination and click Convert. Transfer the finished .3gp file to the device and check both picture and sound.
- When the sample plays correctly, convert the full clip with the same settings.
Expect a smaller picture
Reducing an AVI to 176x144 removes visual detail to suit a small display. Keep your original AVI as the better source for future conversions. If the phone rejects the file, compare its supported audio and video specifications with the chosen preset rather than repeatedly renaming the output.