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This chapter discusses voice messaging in an IP telephony network. The infrastructure for voice messaging, an essential component in any voice network, has recently expanded from the traditional architecture of separate voice mail and e-mail servers and now must support the concept of unified messaging. The Cisco Unified Open Network Exchange (uOne) product is the IP telephony network entrant into the messaging market. This chapter discusses the uOne E architecture and implementation options.
This chapter contains the following major sections:
The uOne E product is actually a multiple product offering with the following features:
| uOne 4.1E Corporate Edition | uOne 5.0E Corporate Edition |
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Note This section details only the initial release of uOne 4.1E Corporate Edition compatible with Cisco CallManager Release 3.0. |
The following characteristics of uOne 4.1E Corporate Edition should be considered in an IP telephony network design:
Each uOne 4.1E Corporate Edition system consists of three main components: the uOne GateServer, the Directory Server, and the Message Store. In uOne 4.1E Corporate Edition and 5.0E Corporate Edition, all these components run on the same server, the Cisco Media Convergence Server 7835 (MCS-7835).
In uOne 5.0E Enterprise Edition, each component resides on its own server. The uOne application runs on the MCS-7835. The customer provides the platforms for the Directory Server and Message Store.
The following descriptions define the four primary processes of the uOne GateServer:
The Directory Server is a vital component in the uOne Corporate Edition architecture. It holds all user information, including user login and password, telephone number, voice mail server, e-mail server, and other information. When a voice session is established with the uOne GateServer, it queries the Directory Server for the user and mailbox associated with a called telephone number. The uOne Directory Server is an LDAPv3 compliant server.
Lightweight Directory Access Protocol (LDAP), an industry standard for storing user and element attributes, is a client-server protocol for accessing a directory service. It was initially used as a front end to X.500, but can also be used with stand-alone and other kinds of directory servers. The LDAP information model is based on the entry, which contains information about some object (for example, a person). Entries are composed of attributes, which have a type and one or more values. Each attribute has a syntax that determines what kinds of values are allowed in the attribute and how those values behave during directory operations. Examples of attribute syntaxes are for IA5 (ASCII) strings, JPEG photographs, u-law encoded sounds, URLs, and Pretty Good Privacy (PGP) keys. For further details, see the "Additional Information" section.
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Note uOne 4.1E Corporate Edition uses the Netscape Directory Server and cannot be integrated into your enterprise directory. In fact, uOne 4.1E Corporate Edition installs the directory as a generic "o=Organization". |
The Message Store is the storage utility for all voice mail. The messages are transferred between the GateServer and Message Store using the Internet standard Simple Mail Transfer Protocol (SMTP) and Internet Message Access Protocol (IMAP). When a caller leaves a message with the GateServer, it is forwarded using SMTP to the Message Store. When a user calls the uOne Corporate Edition system to retrieve voice mails, the GateServer connects to the Message Store using an IMAP4 session. Both of these processes occur even when all components reside on the same physical machine.
SMTP, as defined in RFC 822, is a method of transporting electronic mail between hosts on TCP port 25 of the IP suite.
IMAP, another method of accessing electronic mail from a host, can access and manipulate messages from a variety of client stations without having to download them from the mail server. For more information, refer to the "Additional Information" section.
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Note uOne 4.1E Corporate Edition uses the Netscape Messaging Server. |
This section discusses the use of uOne 4.1E Corporate Edition in the small enterprise of 100 to 500 users and in the larger enterprise of up to 10,000 users.
When uOne 4.1E Corporate Edition is implemented as an IP telephony network voice mail solution, it is configured in an integrated server, the MCS-7835. As shown in Figure 10-1, this server runs all the messaging components: uOne GateServer, Directory Server, and Message Store. It connects to the Cisco CallManager server using the Skinny Station Protocol. In smaller enterprises of 100 to 500 users, there would be a single MCS-7835 running uOne 4.1E Corporate Edition that provides voice mail for all Cisco CallManager users.
There is no support for Cisco CallManager redundancy in the uOne 4.1E Corporate Edition. uOne 5.0E Corporate Edition will support primary, secondary, and tertiary Cisco CallManagers.
The uOne 4.1E Corporate Edition product is sold with 20 ports of voice mail, providing support for 500 users. (One hundred licenses come with the product. For installations of more than 100 users, additional licenses must be purchased.) These ports are typically configured with a block of 20 directory numbers (DNs) from Cisco CallManager. Using extensions 1001-1020 as an example (see Figure 10-2), within Cisco CallManager all users configured with voice mail would have 1001 as their forward-no-answer (FNA) and forward-busy (FB) numbers. Extension 1001 would have its FNA and FB numbers configured as 1002. Port 1002 would have its FNA and FB configuration entered as 1003, and so on, until port 1020 is queried. Port 1020 would have its FNA and FB configured as either 0 (zero) for the attendant or 1001, to cycle back through the uOne DNs to see if any ports are now free. By default, Cisco CallManager cycles through up to 20 FNA/FB ports before sending a busy signal to the caller. This is a configurable value in the Cisco CallManager SCM.ini file.
Cisco CallManager Release 3.0 supports up to 2,500 users per Cisco CallManager or 10,000 users per cluster. In these larger installations, more MCS-7835 servers are needed to provide voice mail. Table 10-1 lists the number of uOne 4.1E servers needed per Cisco CallManager user.
In Cisco CallManager Release 3.0 and uOne 4.1E Corporate Edition, the only way to configure large numbers of users is to mirror small enterprise configurations and give each group of 500 users their own pilot number with 20 associated voice mail ports, which Cisco CallManager uses for forwarding. When configuring large campuses with many uOne 4.1E Corporate Edition servers, voice mail pilot number configuration can be cumbersome. First, taking into account the possible number of users in a Cisco CallManager Release 3.0 environment, it is obvious that many uOne 4.1E Corporate Edition servers may be needed, as shown in Table 10-1.
| Cisco CallManager Users | uOne 4.1E Corporate Edition Servers | Pilot Numbers |
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100 | One MCS-7835 | One with 20 FNA voice mail ports |
500 | One MCS-7835 with additional licenses | One with 20 FNA voice mail ports |
2,500 | Five MCS-7835 servers with additional licenses | Five with 20 FNA voice mail ports each |
10,000 | 20 MCS-7835 servers with additional licenses | 20 with 20 FNA voice mail ports each |
An obvious caveat with this design is that every block of 500 users must have a different voice mail number. Because uOne 4.1E Corporate Edition does not support networking between uOne systems, users cannot send, receive, or reply to voice mails between systems. For larger enterprise deployments, this amounts to isolated islands of 500 users per uOne server, as shown in Figure 10-3.
While it is technically possible to implement multiple disparate uOne 4.1E Corporate Edition systems and scale to a large number of users, we recommended waiting for uOne 5.0E Corporate Edition for installations of more than 500 users.
uOne 4.1E Corporate Edition installations across a WAN environment mirror large campus installations in that every group of 500 users must have separate pilot numbers. Each of these pilot numbers is associated with 20 voice ports and a single server. Because these are uOne 4.1E Corporate Edition servers, there is no voice mail networking between sites. This can be changed by installing the uOne 5.0E Corporate Edition when it is available.
Because uOne 4.1E Corporate Edition supports only the G.711 codec, any users leaving or retrieving voice messages over an IP WAN must use either G.711 or a Catalyst MTP transcoding resource. The Catalyst MTP transcoding resource, described in detail in "Catalyst DSP Provisioning," converts the compressed voice stream to G.711 for the uOne GateServers, as illustrated in Figure 10-4.
For further information on implementing uOne Corporate Edition voice mail in a WAN environment, see "Multi-Site WAN with Distributed Call Processing" and "Multi-Site WAN with Centralized Call Processing."
Posted: Thu Jul 27 15:11:05 PDT 2000
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