Gratis Online SLN naar OGG Converter

Asterisk PBX ‘signed linear’ 8khz, 16-bit signed integer, little-endian raw format.

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.