Instructions on how to properly convert audio files to a low quality meant for phones.
Be sure to try this website first: https://recordmp3online.com/ if it doesn't work try below.
You'll need to get audacity
You'll need to get LAME
1. Drag and drop your audio file into audacity
2. On the bottom left, lower the project rate down to 8000
3. Tracks -> Resample... -> 8000 -> OK
4. File -> Export Audio... -> Name the File in the Save As-> Format: Other uncompressed files -> Options -> Header: WAV -> Encoding: U-Law -> OK -> Save -> OK