How to Convert WAV to GSM. Easy GSM File Conversion Software for PC & Mac.
Alvas.Audio is C# audio library which plays, records, converts and edits sound in PCM, Microsoft ADPCM, IMA ADPCM, CCITT A-Law, CCITT u-Law, GSM 6.10, MPEG Layer-3 (mp3), Dialogic VOX
How to Convert GSM to MP3 Without Quality Loss [Complete Guide]
WAV Format Customization in Audio Converters for Mac OS X - Amvidia