Applies to: Exchange Server 2013
Topic Last Modified: 2012-07-05
Voice Mail Preview is a feature that's available to users who receive their voice mail messages using Microsoft Exchange Server 2010 or Exchange Server 2013 Unified Messaging (UM). Voice Mail Preview enhances UM voice mail functionality by providing a text version of audio recordings. The voice mail text is displayed in an email message within Microsoft Office Outlook Web App, Outlook 2010, and other email programs.
Voice Mail Preview enhancements
In Exchange 2013, UM includes several enhancements to the user interface for Outlook Web App and Outlook clients and improvements to increase confidence and accuracy for Voice Mail Preview. Also, some enhancements to the speech-related services are offered through the Microsoft Speech Platform (Version 11.0) and Unified Communications Managed API (UCMA) 4.0 to enhance grammar generation and language support.
Unified Messaging introduced the Voice Mail Preview feature in Exchange 2010. Voice Mail Preview uses automatic speech recognition (ASR) to add a text version of a voice mail audio file to a voice message. ASR isn't entirely accurate, especially when it's used to record audio over a phone that includes unknown voices and noises.
Some organizations require consistently error-free or near-error-free transcripts of voice mail messages for some, if not all, of their users. The Voice Mail Preview Partner Program helps such organizations meet those requirements. The Voice Mail Preview Partner Program was designed for Exchange 2010 to improve Voice Mail Preview results, but it wasn’t used by Exchange 2010 customers because of the overhead and cost. To address these issues, Exchange 2013 includes the following enhancements for Voice Mail Preview:
- Improved audio normalization Audio
normalization is the process of uniformly increasing (or
decreasing) the amplitude of an entire audio signal so that the
resulting peak amplitude matches a specified target or the norm. UM
normalizes the audio recording before compressing it and sending to
- Enhanced speech recognition By
collecting voice mail messages (only if the Exchange customer
chooses to share this information), the results of the voice mail
previews can be used to add words and phrases to the speech engine.
This is done by setting the VoiceMailAnalysisEnabled
$trueusing the Set-UMMailbox cmdlet or by setting the AllowVoiceMailAnalysis parameter to
$trueon the Set-UMMailboxPolicy cmdlet. Also, Exchange 2013 UM uses information more efficiently from email threads created by a user using Outlook Voice Access. This includes information about the participant’s (Active Directory or personal contact) information (country, city, company), and the phone number of the Outlook Voice Access user.
- Voice Mail Preview confidence The
confidence score is the number assigned by Unified Messaging that
is directly related to the overall accuracy of the transcription.
The confidence calculations that are used by UM have been adjusted
to be more accurate and represent the actual accuracy of a
- Filtering Offensive words are detected and filtered and
the results are cached and stored in the user’s mailbox.
- Hiding the text preview If the
confidence score of a voice mail preview is below a given
threshold, the Voice Mail Preview text will be hidden. If the text
is hidden, the voice message will include text stating that the
confidence of the voice mail was too low for results to be
- Transcription performance Voice Mail
Preview is a CPU-intensive operation that requires roughly twice
the time it takes to process an audio file. If generating the voice
mail preview text takes too long, CPU throttling stops processing
the preview. In Exchange 2010, UM didn’t try to transcribe any
voice message that was longer than 75 seconds. In Exchange
2013, the entire voice message is transcribed, but the text for the
message isn't included if it extends past 75 seconds.
- Color schemes Because of the confusion
over the colors that were used to distinguish between low, medium,
and high confidence for a voice mail preview, the color scheme has
been removed in Exchange 2013 for Outlook Web App and Outlook.