Gratis Online VMS naar OGG Converter

Used in Germany to compress speech audio for voice mail. A self-describing variant of cvsd (Continuously Variable Slope Delta modulation).

This format is free, which apparently is one of the reasons for its popularity. The used codecs supports variable bit rates (as a default), and .ogg files usually play back easily on all platforms. All things being equal, the sound quality exceeds that of mp3 somewhat.