Core Issue
When Automatic Gain Control (AGC) is used, adjustments to recording or playback audio can modify the incoming audio stream before it reaches the AGC operation. This causes extreme volume levels in the message, as heard in this fuzzy voice sample.
Resolution
If the Cisco Unity version is 3.1(2) or later, and AGC is active, the WaveDBGainPlayback and WaveDBGainRecord values should always be set to 0.
For information on adjusting AGC settings, refer to the Automatic Gain Control section of Audio Quality.
For more sample voice quality symptoms, refer to Recognizing and Categorizing Symptoms of Voice Quality Problems.