Working with sound files in a telephony environment can be challenging. Fortunately there are tools, tips, and tricks that can help you out.
- Sox - SOund eXchange, great for manipulating sound files
- Converting WAV files using sox: audio_conversion_cheat_sheet
- Audacity - Graphical sound editor and analysis software
- Ecasound - Multi-track audio processor
- Converting wav files. See this from voip-info.org