Download free Nokia Multimedia Player with 3GP support.
Click here to download Nokia Multimedia Player
This is normal video player for PC platform (Windows OS), but it has several additional functions (conversion to 3gp format).
Step 1. Download and install player.
Step 2. Launch Nokia Multimedia Player. Open your video file (avi, mov or mpg).
Step 3. Press File -> Save as...
Step 4. Enter the name of your 3gp file, choose resolution and size limit:
MMS 64KB, 128*96
MMS 95KB, 128*96
MMS 95KB, 176*144
Custom 200KB, 128*96
Custom 200KB, 176*144
Custom 300KB, 128*96
Custom 300KB, 176*144
No size limit, 128*96
No size limit, 176*144
Step 5. Click Save. Wait several minutes. File is converted. That's all!