This document describes techniques to troubleshoot problems that you
might experience with Cisco Unity audio quality. Audio quality for the Cisco
architecture for voice, video and integrated data (AVVID) solution is a
perceptual measure of how good audio sounds as it reaches the intended
recipient. With any subjective evaluation, it is most important to realize the
measurable areas of audio quality and identify how these areas affect the
reported audio quality problem.
For example, if a reported problem is “loud Unity system prompts,”
volume can be described as the problem area that impacts audio. If you isolate
the investigation to volume levels, you can take the steps in this document to
further investigate what part of the environment might change volume
After you categorize the type of audio quality issue, you can determine
the source of the audio distortion thorough a process of elimination. This can
be a complex process, depending on the number of devices in any AVVID
deployment that originate, control, or deliver audio streams to Cisco Unity.
Keep in mind the complexity of the environment and the various paths the audio
stream take, to more quickly identify the source of audio distortions. Each of
the known areas of audio quality issues in this document follow this logic as
For example, when the problem area that affects audio quality is known
to be volume, there are several ways to change volume in the AVVID environment.
The Volume Levels and Gain Control section first
addresses any potential volume changes Cisco Unity can make to an audio stream;
it then covers other known sources of volume modification that can impact audio
received by Cisco Unity. If none of the topics in that section correct the
audio distortion, check the other listed symptoms for a similar sounding audio
Readers of this document should have knowledge of these topics:
How to set Cisco Unity traces
How to use Netmon (from the Microsoft Windows 2000 Resource
How to work with the Windows
In addition, you should know this information about the Cisco Unity
installation, before you complete the troubleshooting in this document:
Cisco Unity version number
Integration type including the Telephony Application Program
Interface (TAPI) service provider (TSP) version number
Cisco Unity message recording format (codec type)
Codices used within the integration and any other regions of the
Installation history (new install, upgrade)
Local topology information can be also useful to understand the
pathways that audio travels to Unity
The information in this document is based on these software and
Cisco Unity version 18.104.22.168, 3.x versions through 3.1(5), and 4.x
versions through 4.0(2).
Netmon Network Analysis Tool from the Windows 2000 Resource
Sniffer Pro version 4.5 from Network Associates, Inc.
Cisco Unity utility AudioStat, available in Cisco Unity 4.0(1) and
later versions; and Capripper utility, available in Cisco Unity 4.0(2) and
Note: Not all are required for every type of audio quality issue
The information in this document was created from the devices in a
specific lab environment. All of the devices used in this document started with
a cleared (default) configuration. If your network is live, make sure that you
understand the potential impact of any command.
Refer to the
Technical Tips Conventions for more information on document
Note: The links in this document contain the most current information known
on the type of audio distortion possible in the environment. Review the
symptoms of each before you attempt troubleshooting steps.
This section describes volume level and gain control troubleshooting
The symptom of this problem area relates to unexpected changes in the
volume level of a voice mail message or volume levels from Cisco Unity measured
as “too loud” or “too quiet.”
Volume level and gain control issues are most often reported when audio
is too quiet in a message for the user to understand the content. There are
also possible fluctuations of volume that could be reported as creating a
“garbled” message, where the volume goes up or down regardless of the volume of
a speaker’s voice (for example: Audio Volume Fluctuation on Phone
Cisco Unity versions 3.1(2) and later also contain an automatic gain
control (AGC) feature, which might contribute to fluctuations in volume if
incorrect settings are introduced in the configuration. This is most often
noted by large increases in volume at the end of a message (for example:
Audio Volume Fluctuation from Incorrect
Finally, adjustments to recording or playback gain where AGC is used
can modify the incoming audio stream before it reaches the AGC operation. This
can cause extreme volume levels in the message (for example:
Audio Volume Extremes from
Incorrect TSP Settings).
Audio volume distortion can occur at any point in a voice stream, from
an originating cellular phone on an external call through to the IP phone that
receives a message from that caller. Volume gain might be distorted with an
increase or decrease in volume through these devices:
IP Phone (no configurable gain)
Analog gateways (gain increase or decrease)
Digital Signal Processors (DSPs) (gain increase or
Unity TSP (either on-board AGC through a Dialogic TSP or playback and
record gain values in Cisco Unity TSP registry values)
Unity AGC (increase and decrease through AGC)
PSTN devices (unknown, and usually not programmatically altering
volume, although “noise-reducing” microphones can adjust input
Cisco Unity versions later than 3.1(2) with AGC enabled have a target
nominal volume level of –26 decibels by default. When other devices in the
deployment might also control gain levels, it can be easiest to isolate a
volume issue by first disabling these settings on gateways that deliver audio
to Cisco Unity.
Note: When the gain levels vary on different gateways, the settings should
be noted so that you can return the levels to the original values after you
troubleshoot (if needed).
Note: Ensure that you do not increase the volume of speakers or headphones
while you are troubleshooting this type of issue.
Use these steps to troubleshoot volume level and gain control
Identify which audio streams are affected by the volume
Are all audio streams from Cisco Unity at a low volume? If only a
particular part of an audio stream is affected (for example, only Cisco Unity
system prompts or only messages), proceed to Step 2.
When all audio from Cisco Unity is at a low volume and
phone-to-phone volumes are low, first check gain settings on gateways in the
Use Cisco Unity to validate volume levels:
During a maintenance window, enable the Cisco Unity Diagnostic
Tool (UDT) for MiuIO Miscellaneous (23).
This diagnostic reports the input power levels of all incoming
audio samples, as shown in this example:
MiuIO 23 [Thread 0x00000EB0] [Port 2] [AvWav: Miscellany]
Power = -31.012355dB Gain adjustment = 5.000000dB.
From a single source (a local IP phone, for example), leave
messages for Cisco Unity with similar volume levels. Applying a steady speaking
voice to say the same 10 to 15 second phrases.
An internal call should serve as the “control” point for volume
on the IP network. Calls that are made out through the PSTN and back into Cisco
Unity show the volume levels that come through any number of analog
After you complete all of the test calls, stop the UDT trace
and gather the diagnostic for the time period that the calls were
Find the individual calls by their timestamp in the diagnostic,
and view the Power and Gain
adjustment settings for each call.
If calls consistently have a Gain
adjustment of 5db or greater, either the gain on the gateways
need adjustment or the Cisco Unity TSP registry settings should be checked
(proceed to Step 2).
When only audio from Cisco Unity is at a low volume, check the
TSP playback and record volume levels from the registry key on the Unity
Run Regedit and verify the keys in
HKEY_LOCAL_MACHINE\SOFTWARE\Cisco Systems, Inc.\Cisco TSP.
The WaveDBGainPlayback and WaveDBGainRecord keys should both
have the value of 0.
A clear example of when this setting can affect audio is when a
gateway has a positive gain applied and the WaveDBGainRecord has a negative
value. The volume level is incorrectly being adjusted at the gateway and Cisco
Unity. A volume increase applied at the gateway followed by a volume decrease
at the TSP could result in the same lower volume level going into Cisco Unity
as that which entered the gateway.
In the same way, when a gateway has negative gain applied and
WaveDBGainRecord has a negative value, any value on the WaveDBGainPlayback
could be useless to adjust low volume messages played from Unity.
Finally, a negative WaveDBGainRecord value with a negative
WaveDBGainPlayback value will always decrease the volume of any audio played
out of Unity. Older TSP versions (pre 3.0) might retain a WaveDBGainRecord
value of 5, which causes distorted volume levels on recorded messages.
Note: If the Cisco Unity version is 3.1(2) or later and AGC is
active, the WaveDBGainPlayback and WaveDBGainRecord values should always be 0.
As with the multiple points of volume adjustment described in the previous
paragraph, if the audio volume level is already manipulated by AGC, then it is
not recommended that you adjust either recording or playback volume levels in
Check if the registry setting values for AGC are set incorrectly.
The bad values are usually:
If so, change the registry settings to the correct values, as
described in the AGC Registry Keys table that can be found in the
Note: If the quality of the prompts are unacceptable when you use the
G.729 codec, you can
the codec to G.711 for better audio quality.
Identify which part of the audio stream is affected by the volume
change: Cisco Unity system prompt, messages left for subscribers from outside
the local network deployment (analog or digital), or messages left for
subscribers from other subscribers.
When only messages from callers outside of the VoIP deployment have
volume levels above or below messages left by subscribers or Cisco Unity system
prompts, verify gain levels on gateways that deliver this audio:
If Cisco Unity Legacy PBX integrations are present, refer to
Unity-Legacy PBX Integration: Adjusting the Volume in Registry for more
If all messages are affected, but Cisco Unity system prompts are
at an acceptable level, check the version of Unity currently running.
AGC default settings should be checked, if the Cisco Unity
version is 3.1(2) or later. Refer to these documents for more
You should verify prompts and TSP gain levels, if the Unity
version is earlier than 3.1(2). Refer to
Decision Tree for Cisco Unity 2.46 and 3.0x for more information.
If only some messages are affected, verify the phone load
deployed for DDTs issue Cisco bug ID
(registered customers only)
See the Connectivity, Jitter, Packet
Delay, and the ‘Garbled Message’ section of this document, if the volume
level is fluctuating quickly and consistently within any message. Even though
the volume is actually zero in many parts of these types of distorted messages,
it can be perceived as a volume fluctuation issue.
If only some subscribers are affected by different volume levels
on phone and computer playback, refer to
Unity ViewMail for Outlook (VMO) Audio Volume Settings for more
Note: If you experience a bad quality for
on Hold (MOH), make sure that the music audio source files comprise
.wav files in one of these formats:
Refer to these documents for more information about volume level and
gain control issues:
This section describes audio connectivity distortion troubleshooting
“Garbled message” is most often reported when a message left for a
Cisco Unity subscriber is either missing enough audio content to be considered
unintelligible or when the packets are interleaved such that the content sounds
out of order. Rather than longer specific periods of silence in the message,
which might be related to volume levels (as previously noted), the garbled
message might have other distortions present.
A bad network interface card on a Cisco Unity server is the source of
audio distortions heard in this example: Audio Distortion Due to a Faulty Network
Interface Controller (NIC).
This example is notable because of the distortion that is inserted for
brief intervals at various points in the message. Not only are missing packets
the cause of silence insertions, but additional signals from other audio
streams—which the NIC is delivering incorrectly—are heard as “pops” throughout
Notice the difference in this example, which contains distortions due
to packet delay in the network: Audio Distortion Due to Packet
This example is notable for the silence insertions—during large packet
delays—that are increasing throughout the message.
Audio connectivity distortions can also occur at several points in a
network from a gateway receiving an external call through to the IP phone that
receives a message from that caller. Use these steps to troubleshoot audio
connectivity distortion issues:
Identify which audio streams are affected by the garbled
Are all audio streams from Cisco Unity garbled?
When only Cisco Unity system prompts are garbled, verify the fix
for garbled prompts playing from Unity through a Catalyst 6000, refer to DDTs
issue Cisco bug ID
(registered customers only)
The distortion associated with this defect is heard in this example:
Unity Garbled Prompts
Where all audio from Cisco Unity is garbled and phone-to-phone
audio is also garbled, verify the duplex settings on the Unity NIC
configuration and on the switch port to which Unity is connected. These
should not be set to auto-negotiate, but rather to
hard-coded values (usually 10/100 full duplex).
This eliminates the possibility that auto-negotiation of packet
delivery is a cause or contributor to distortion of the audio streams.
If the distortion continues after taking the step above, check
the network topology and available bandwidth to Cisco Unity. Check relevant
gateways for alignment errors.
If alignment errors are found on any switch ports, and the Cisco
Unity server is an HPQ DL380G2 (MCS7837, MCS7847), then the distortion could be
associated with an incorrect NIC driver. These errors are typically reported as
alignment errors, runt packets, or Frame Check Sequence (FCS) errors by
switches. The NC-Series NIC statistics might report the errors as either
Transmit Underruns or Receive Overruns. Check the N100NT.SYS driver on the
Cisco Unity server. If it is version 5.30.74.001, the solution is to install an
older version of the driver from:
If the distortion continues or the NIC driver downgrade does not
apply to the hardware, the audio stream that is entering the Cisco Unity server
must be validated for any distortion per the instructions in the next step
Identify whether the source of distortion is internal or external
to Cisco Unity.
This is a simplified description of the audio stream path from the
Cisco Unity NIC to a wave file:
Incoming audio stream from the network —>
NIC —> Cisco Unity’s avaudio.sys
Cisco Unity’s avaudio.sys —> (through Microsoft Windows wave
driver) to UnityAvWav
UnityAvWav converts the stream to PCM, applies AGC, and converts
the audio to the destination codec format —> temporary file
Temporary file completed at end of recording —> wave file
created and passed to the mailstore, after leading or trailing silence is
When you identify the inconsistencies in the audio stream based on
the different paths it takes before it becomes a wave file delivered through
email, you can isolate the source of distortion to one of these reasons:
An objective comparison of the audio streams as they pass through
the components is necessary to confirm any of these sources.
Caution: You should not use the methods in Steps 3 and 4 as general
troubleshooting methods, if other steps have not been attempted. To capture
audio traffic without discretion is not recommended, and it might affect the
Caution: You should use a maintenance window when you do Steps 3 and 4, as
the actions could impact service.
Use a test phone and test subscriber to obtain the best objective
measure of audio quality, unless a specified endpoint has been identified as
the source of distortion.
Collect the incoming audio stream from the network to the NIC, for
a comparison of external audio to audio written to the mailstore.
Span the Unity port at the network device to which Cisco Unity is
connected, and collect the packets through a Sniffer. You can also use Netmon
(from the Microsoft Windows 2000 Resource Kit) from any Windows 2000 server
that is external to the Unity server, to collect the data going to the Unity
Note: It is recommended that you only run Netmon on the Cisco Unity
server itself after the audio stream has been collected
external to the Unity server NIC.
For packet captures, use a capture filter to take UDP packets from
any source with a destination of the Cisco Unity server IP address. Save the
captures from the testing time period, to compare them to the data that you
will collect in the next procedure.
In order to collect the incoming audio to the Cisco Unity wave
driver—Use Netmon on the Cisco Unity server to collect the data incoming UDP
audio streams. After Netmon is installed, complete these steps to configure
Copy the RtpParser.dll file to
…\WINNT\system32\NETMONFull\PARSERS. This file is available in the Audio
directory of the Cisco Unity \Commserver\Utilities
Choose Start > Control Panels > Administrative
Tools > Network Analysis Tools, to open
Select the appropriate interface and capture only UDP traffic
In order to collect the audio stream the wave file created
(written by the Cisco Unity wave driver)—Most often, problem audio is reported
from a user directly as they receive the voice mail(s) that contain distortion.
If so, request these messages to help isolate the issue. For further
troubleshooting, it is best to create a test subscriber account that you can
access from a mail client, so that you can save the voice mail wave files to
disk. If this is not possible, have the messages forwarded from this test
mailbox to an outside address, to assist in the collection of the wave files.
Finally, if neither of these are possibilities (where a voice-mail only system
is in place, for example), this procedure allows for direct access to the wave
files before they are delivered:
Stop the Microsoft Exchange Information Store service from the
Exchange mailstore with which Cisco Unity is homed.
This places Cisco Unity into the Unity Message Repository (UMR)
mode, where all messages sent to subscribers go first to the
…\Commserver\UnityMTA directory. For more information, refer to
to Start Cisco Unity in UMR Mode.
Collect the resulting wave files from this directory after test
messages are sent.
Caution: No messages are delivered on the Exchange mailstore during
this time. This procedure impacts any incoming call—use only during a
Restart the Microsoft Exchange Information Store service after
the tests are completed.
In order to compare the collected data, use the Capripper utility
to convert the packet capture files into wave files (also found in the Audio
directory of the \Commserver\Utilities directory in Cisco Unity version 3.1(5)
Copy the capripper.exe file and the cap file to
be decoded into a new directory.
Drag the .cap file containing the test audio streams onto the
capripper.exe to create a series of .wav files named for the endpoints in each
call, as shown in these screens:
Listen to the test calls from the packet capture and from the
mailstore. If there is any difference between the stream collected from the
network to the NIC and the stream collected from the NIC to the Unity wave
driver, there is likely a hardware issue with the NIC.
For instance, this example—Packet Capture Encoded to a Wave
File—collected from traffic to the NIC, compared with this example—Unity
Message Wave File—collected from the Cisco Unity system, shows an issue
with a NIC hardware failure. In this case, if the server has a dual-NIC
configuration, disable the currently used NIC and enable the second NIC. If no
more reports of distortion occur, the NIC is the source of the audio
distortion. If the server has only one NIC available, install a PCI-NIC where
possible and switch all traffic to run through this interface. If no further
distortion is heard, contact Cisco Systems Technical Support to report the
When the previous steps show that audio that enters the Unity
server and passes through the NIC is of acceptable quality, but distortions
still exist in the wave file written to the drive, you must collect the audio
stream with Netmon. Determine the arrival time of the packets for the audio
stream. If there is more than 20ms of delay between packets, the wave driver
might insert silence into the wave file as a normal operation. If packet
captures show delay as the cause of multiple silence insertions, DDTs issue
Cisco bug ID
(registered customers only)
addressed in Cisco Unity version 3.1(5), might broaden the window for packets
to be received by the wave driver. Although you can set a greater packet delay
with this registry key, this indicates unacceptable delay in the network that
you should investigate.
In order to investigate the delay, run the AudioStat utility
(found in Cisco Unity versions 4.x and later) from the Audio directory of the
\Commserver\Utilities directory. This tool displays average delays and silence
insertions for each recording along with the source IP address of the device
that is sending audio to Cisco Unity.
These screens show the AudioStat
If any single device shows increased latency, investigate that
link in the network. The AudioStat utility helps to isolate where in the
topology latency is introduced.
Another frequent cause of jitter and choppy voice messages is
when Voice Activity Detection (VAD) is enabled. You can overcome this when you
if bandwidth is not an issue.
Refer to these documents for more information about audio connectivity
This section describes dual tone multifrequency (DTMF) recognition and
voice mail responsiveness troubleshooting techniques.
DTMF recognition and voice-mail response issues that affect audio
quality are most often reported as one-way audio during a call to Cisco Unity
or a lack of response from the voice mail system after digit entry by the
caller. The voice mail responsiveness issues can sometimes be correlated to the
integration factors listed later in this section, but they most often might
depend on Exchange deployment configuration as described in
Unity: Delays in the Subscriber Conversation.
Silence suppression, voice activity detection (VAD), and comfort noise
might also contribute to message clipping or cut off (where the system is
recognizing silence as a call termination event). This section contains a list
of documents to assist with configuration and troubleshooting.
Refer to these troubleshooting documents, if the Cisco Unity
integration involves a legacy PBX:
Refer to these troubleshooting documents, if the Cisco Unity
integration involves Cisco CallManager through the Cisco-Unity TSP:
If all callers hear a reorder tone calling Cisco Unity, refer to
Unity Ports Lock Up After Enabling G729a Codec.
If callers hear a continuous ring tone calling Cisco Unity, refer to
Unity and CallManager IP Integration: Unity Voicemail Port Not
If callers hear one-way audio, or Message Waiting Indicator (MWI)
lamps do not light, refer to
Troubleshooting Dual NICs for Cisco Unity.
If callers hear prompts but can not record messages or greetings,
Unity with Cisco CallManager: One-Way Audio.
If some subscribers hear a reorder tone calling Cisco Unity, and
WaveOutSupportsVolume errors appear in the Event log, refer to DDTs issue Cisco
(registered customers only)
If some outside callers hear a reorder tone calling Cisco Unity,
From the PSTN Don’t Get Unity Voice Mail, but Local IP Phone Calls Work
If calls to Cisco Unity end after thirty seconds, refer to
Unity: Voice Mail Stops After 30 Seconds.
If subscribers can not log in or callers can not transfer to desired
extensions, refer to
Unity with CallManager Problem with DTMF.
If subscribers that use speed control press a key during message
playback and are disconnected, refer to
Field Notice: Cisco Unity Playback
Speed Controls May Drop Callers or Lock up All Unity
For more information about DTMF recognition and voice mail
responsiveness issues, refer to these documents:
This section describes echo troubleshooting techniques.
Echo is included here as a general audio quality issue that affects
AVVID deployments, which should be familiar to anyone that troubleshoots audio
quality issues. It has yet to be the type of issue that could ever impact a
message left on a Cisco Unity system. Echo can occur during an IP call when the
distortion is generated through digital or analog gateways.
For more information on the sources of echo and troubleshooting, refer
to these documents: