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Design Guide for Cisco Unity Release 5.x
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Index
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Preface
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Design Guide Overview
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Cisco Unity Concepts
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Network Infrastructure Requirements
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Designing a Cisco Unity System with Exchange as the Message Store
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Designing a Cisco Unity System with Domino as the Message Store
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Integrating Cisco Unity with the Phone System
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Cisco Unity Failover and Standby Redundancy
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Voice-Recognition Access to Cisco Unity
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Migrating to Cisco Unity from Another Voice-Messaging System
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Design Differences Among Versions of Cisco Unity
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Feedback
Table Of Contents
Network Infrastructure Requirements
Availability of Network Resources
Domain Controller Access and Availability
Availability of Message Store Servers
Using Firewalls with Cisco Unity
Sizing and Scaling Cisco Unity Servers
Maximum Number of Users on Dedicated Domino or Exchange Servers
Storage Capacity for Voice Messages
How Codecs Affect the File Size of Voice Messages
TTS, TTY, Pocket PCs, and Hand-Held Computers
Interoperability Among Multiple Voice-Messaging Systems
Network Infrastructure Requirements
See the following sections:
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Availability of Network Resources
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Availability of Network Resources
The following network resources must be available at all times and in close physical proximity to Cisco Unity (over a local area network, not a wide area network), or Cisco Unity functionality will be impaired:
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Name Resolution
Cisco Unity must be able to find the servers it interacts with by resolving the names of those servers to IP addresses, unless the Cisco Unity server is not connected with the network. For example, Cisco Unity can send messages from outside callers to the message store server on which the mailbox of the recipient is homed only if Cisco Unity can find that message store server. Name resolution is also used when:
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The Cisco Unity server must use Dynamic DNS (DDNS) or another version of DNS that supports dynamic updates as described on the Microsoft website. Simply creating a host file on the Cisco Unity server is not sufficient.
When Domino is the message store, note the following:
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When Exchange is the message store, note the following:
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Domain Controller Access and Availability
For all configurations and all message stores, Cisco Unity must have access to a Windows domain controller to authenticate service accounts and, when Exchange is the message store, to authenticate subscribers.
When Domino is the message store, subscribers can be authenticated for GUI-based access to Cisco Unity by using either Windows authentication or Domino authentication; Domino authentication does not require access to a Windows domain controller.
Availability of Message Store Servers
When Cisco Unity is installed, the installer specifies one Domino or Exchange server that Cisco Unity connects with; this is known as the partner Domino server or the partner Exchange server. The partner server is the home of the Cisco Unity system mailbox (alias: Unity_<ServerName>. The Unity system mailbox is the mailbox that originates voice messages from outside callers. The partner server is also the home for default mailboxes and distribution groups (Cisco Unity distribution lists) that are created during installation. If Cisco Unity subscribers are homed on servers other than the partner Exchange server or the Domino mail drop server, all voice messages from outside callers pass through the partner server or the mail drop server on their way to the home servers for Cisco Unity subscribers.
When the partner Exchange server, the mail drop Domino server, or a message store server on which Cisco Unity subscribers are homed is unavailable, Cisco Unity functionality is affected in the following ways:
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Using Firewalls with Cisco Unity
Revised May 6, 2008Cisco Unity can coexist with firewalls. However, note that Cisco Unity should never be deployed outside of a firewall. Doing so can expose the Cisco Unity server to unwanted intrusion from the Internet, even if the server is hardened.
For detailed firewall requirements, see the following sections in the System Requirements for Cisco Unity at http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_installation_guides_list.html:
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Sizing and Scaling Cisco Unity Servers
When sizing a Cisco Unity server, follow these guidelines:
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For a list of servers that meet Cisco Unity specifications, see the Cisco Unity Supported Platforms List at http://cisco.com/en/US/products/sw/voicesw/ps2237/products_data_sheets_list.html.
Maximum Number of Users on Dedicated Domino or Exchange Servers
You should not allow the Domino or Exchange servers to service the maximum number of Domino or Exchange users that IBM Lotus or Microsoft allow. In addition, servers qualified by Cisco as Exchange message store servers for use with Cisco Unity have a maximum number of Exchange users, and the customer should not allow the number of users on these servers to reach the maximum.
You should also be careful not to exceed the disk capacity for the information store. For example, in order to enable recovery if the information store is corrupted, Microsoft recommends that the total size of an Exchange information store never exceed 50 percent of the capacity of the drive on which the information store is installed. For more information, see the Microsoft website.
Storage Capacity for Voice Messages
For Cisco Unity systems that are configured for Voice Messaging, base the server requirements on the total number of voice storage minutes required for each subscriber. A supported Cisco Unity server generally provides storage for 20 to 30 minutes of voice messages per subscriber for the maximum number of subscribers supported on that server.
For Cisco Unity systems that are configured for Unified Messaging, it is not possible to base server requirements on the total number of voice storage minutes required for each subscriber, because the message store also includes e-mail messages and possibly faxes. However, you can calculate the storage requirement for the desired number of voice storage minutes and add that to the current mailbox limits.
If the customer is replacing an existing voice messaging system with Cisco Unity, it may be possible to obtain information from the existing system on the average number of minutes of voice messages that subscribers currently have. You can then multiply the average number of minutes by the recording size per minute—according to the codec that Cisco Unity will use to record messages—to arrive at the average amount of disk space required for voice messages per subscriber.
Start with a one-to-one correlation of legacy voice messaging system to Cisco Unity. If the legacy system handles a larger capacity than the largest Cisco Unity server, consider splitting the legacy subscriber population onto more than one Cisco Unity server by extension number ranges or prefixes. It is not necessary to segment subscribers onto backend message stores by extension number ranges or prefixes but it may be easier to manage.
For more information, see the "How Codecs Affect the File Size of Voice Messages" section.
Number of Voice Ports
To determine the number and configuration of voice ports required, you can start with the existing voice messaging system, if applicable. This may give you some idea how many ports are required for taking voice messages, for turning message waiting indicators on and off, and for message notification.
In a Unified Messaging configuration, Cisco Unity uses telephone record and playback (TRAP), to allow subscribers who use Notes or Outlook for voice messaging to play and record voice messages over the phone rather than by using speakers and a microphone. This feature is especially desirable when subscribers work in cubicles, where there is a lack of privacy. However, when a subscriber plays or records a message by using TRAP, a port on the Cisco Unity server is used. (No port is used when a subscriber uses speakers and a microphone to play and record messages.) If the customer wants subscribers to use TRAP, calculations for the total number of voice ports required will need to take this into account.
For Cisco Unity failover, the primary and secondary servers must have the same number of ports.
In some cases you might find that an existing voice messaging system has more ports than the current maximum number of voice ports on a Cisco Unity system. In this case, the customer can purchase additional Cisco Unity servers and connect them by using Cisco Unity Digital Networking.
Audio Codecs
An audio codec is an algorithm that encodes and decodes (and compresses or decompresses) audio data. Cisco Unity uses audio codecs with streaming (live conversation) and for WAV-file voice messages. Cisco Unity supports the following audio codecs:
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In general, choose an audio codec based on available storage capacity for voice messages and on available network bandwidth. We recommend using G.711 whenever possible because of its excellent quality for recording and playback. However, if other considerations prevent the customer from using G.711, it is fine to use G.729a, which is also a voice-quality codec. (A large-scale or multiserver deployment may require the use of more than one codec.)
The rest of this section discusses some of the issues to consider when choosing a codec. For a more thorough analysis, see the Audio Codecs and Cisco Unity white paper at http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_white_papers_list.html.
For information on how codec choice affects Active Directory, see the applicable Active Directory Capacity Planning white paper at http://www.cisco.com/en/US/products/sw/voicesw/ps2237/prod_white_papers_list.html.
How Codecs Affect the File Size of Voice Messages
Stored voice messages can consume considerable amounts of disk space. The amount of storage a WAV file uses depends on what kind of compression the codec uses, if any. The higher the compression, the smaller the file and the smaller the disk-space impact on the database and at the subscriber workstation. However, some sound-quality reduction and some CPU processing overhead may result when compressing messages during recording and decompressing at playback.
As illustrated in Table 3-1, voice messages that are recorded in G.711 Mu-Law and A-Law require the most disk space to store, while G.729a offers the smallest file size.
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TTS, TTY, Pocket PCs, and Hand-Held Computers
For Cisco Unity sites using Text to Speech (TTS), any supported codec can be used to record messages. However, TTS output is currently available only in G.711 and G.729a audio formats.
For Cisco Unity sites using TTY, G.711 is required. The TTY standard does not support other codecs.
GSM 6.10 is supported for playback on a Pocket PC, and is a higher quality recording format than MP3. G.711 and G.729a usually are not compatible with hand-held computers.
Interoperability Among Multiple Voice-Messaging Systems
If multiple Cisco Unity servers will communicate with one another via Cisco Unity Digital Networking or VPIM, or if Cisco Unity will communicate with other voice-messaging systems by using AMIS, the Cisco Unity Bridge, or VPIM, you must choose a compatible codec. Table 3-2 shows a summary of codec considerations for Cisco Unity networking options.
