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Cisco Unity volume level problems

Core Issue

Volume gain, which results in an increase or decrease in volume, can be distorted through these devices:

  • IP phones—there is no configurable gain.
  • Analog gateways—the gain can increase or decrease.
  • Digital Signal Processors (DSPs)—the gain can increase or decrease.
  • Cisco Unity Telephone Application Programmable Interface (TAPI) Service Provider (TSP)—either on-board Cisco Unity Automatic Gain Control (AGC) through a Dialogic TSP or playback and record gain values in the Cisco Unity TSP registry can be modified.
  • Cisco Unity AGC—the volume can be increased and decreased through the AGC.
  • Public Switched Telephone Network (PSTN) devices—volume is usually not altered and the process by which it can be is unknown.


These are the Cisco Unity audio problems experienced:

  • Low volume level
  • High volume level
  • Volume levels that fluctuate

Low volume levels are the most common problem experienced, while volume levels that fluctuate can also be perceived and reported as garbled voice.

Note: Be aware that multiple sources usually contribute to audio volume problems. These issues can occur at any point in a network, from a cell phone on an external call to the IP phone that receives a message from that caller.

In order to resolve the Cisco Unity volume problem, complete these steps:

  1. Identify whether only Cisco Unity is affected by the volume problems.

    These are the main cases and actions related to this issue:

    • If Cisco Unity and phone-to-phone volumes are low, first check gain settings on the gateways in the environment, particularly if messages from only callers outside of the VoIP deployment are affected.

    • If only Cisco Unity audio volumes are low, run Regedit, browse to HKEY_LOCAL_MACHINE\SOFTWARE\Cisco Systems, Inc.\Cisco TSP and confirm this information:

      • WaveDBGainPlayback is 0, unless otherwise needed.

      • WaveDBGainRecord is 0, unless otherwise needed.


    • When these values are checked, keep in mind that they offset each other.

    • While other devices in the deployment can also control gain levels, it is easiest to disable settings on gateways that deliver audio to Cisco Unity. This quickly isolates a volume issue.

    • Cisco Unity versions later than 3.1(2) have AGC available.

    • If AGC is enabled, the target message recording level is 26 decibels, by default.

    • If AGC is enabled, the WaveDBGainPlayback and WaveDBGainRecord values must always be 0.

  2. Identify the particular Cisco Unity functions affected by the volume problems.

    These are the main cases and actions related to this issue:

Refer to these documents for more information:

CallManager Versions

CallManager 3.x

Unity Version

Unity 4.x, Unity 3.x

Version history
Revision #:
1 of 1
Last update:
‎06-18-2009 03:49 PM
Updated by: