Currently they are being delivered in GSM format.. but the hope is to release them in lots of different formats, u-law, a-law plus many more that Asterisk uses natively.

The original recordings, where recorded at 44100kHz  at 32bit, this gave us the highest quality we could ever need to keep the voice quality good, when it was re-encoded to the other formats we needed.

All File Format:
We are using sox to re-encode and we apply the following options to the files:

• Re sampling down to 8kHz
• Normalization
• Applying a Low Pass filter to 2kHz

There are the normalized wav files in the SVN repository and you can encode them into anyformat you like

Please visit the Known Issues page for some bugs for playback with Asterisks with no timing device installed