February 1998

BY LLOYD FLORENCE

As with any application that straddles the domains of the IT manager and the telecom manager, selecting a unified messaging system can be a daunting task. The decision process is further complicated by the fact that different vendors have chosen different product architectures, each with its own merits and shortcomings. This article describes some of the factors to consider when selecting a unified messaging system that best fits in with the IT infrastructure of your company.

INTRODUCTION
Messaging systems in any media have a few common architectural elements such as a message transfer agent that delivers messages from a sender to the message recipients, passwordprotected mailboxes for storing messages, and directories for validating addresses during message composition. Notwithstanding these similarities, messaging systems are tailored to accommodate the media they support. Most voice messaging systems provide many attributes associated with the telephony world such as high reliability, automatic recovery processes, and easy hookup to PBX and central office switches, as well as a host of telephone-oriented features such as lighting a message waiting indicator on a telephone set when a new message arrives, notification of new messages through a paging service, and, more recently, speech recognition interfaces for mobile users.

With PCs as their primary access device, LAN-based e-mail messaging systems exhibit characteristics that are more prevalent in the data world such as easy hookup to an intranet, linkages to a corporate directory, support for a variety of e-mail transport protocols such as SMTP and X.400, as well as email server access protocols such as POP3 and IMAP4. In addition, email systems provide features such as archival of read messages, support for binary MIME attachments, and transmission to external e-mail users through mail gateways.

Unified messaging combines the best features of voice mail, fax mail, and email messaging systems into a single application. Messaging “inbox” clients, such as Microsoft Exchange and Lotus Notes, display voice message details such as the time of the call and the caller’s name or telephone number. This gives users helpful information which can be used to determine the order in which to play new messages.

For example, a message left by a customer at noon might take precedence over a message left by a personal acquaintance earlier in the day. Voice messages can either be played over a telephone or through speakers on a multimedia PC. Voice message notification techniques, such as paging, are used for e-mail, so that users can program their inbox to notify them as soon as a particular e-mail arrives. Using simple commands on a telephone keypad, a user can send new e-mail to a fax machine at the front desk of a hotel.

Combining voice, fax, and email messaging systems can be achieved using different product architectures. Some unified messaging product architectures have a strong IT orientation, treating voice messages as audio files attached to e-mail messages. Others have a strong telecom bias, treating text and binary data as other types of media to be handled by the messaging infrastructure of a voice or fax messaging system.

Since any computer product must fit in with the IT infrastructure of a corporation, it is important to understand the implications of each unified messaging product architecture on the critical factors that affect corporate IT purchase decisions, namely, product reliability, operating costs, and user acceptance. It is also helpful to understand what factors may not be that critical, such as media conversion.

PRODUCT RELIABILITY
The reliability of most telecommunications equipment and voice networks exceeds that of computer equipment and LANs. While it is rare not to be able to access voice messages through a telephone set, it is far more common to encounter problems printing a file or accessing e-mail because the LAN is down or the server is unavailable. Some recently announced unified messaging products store all voice, fax, and e-mail messages on the email server. Unfortunately, this tightly coupled architectural approach sacrifices product reliability since the voice and fax messaging systems are only as reliable as the e-mail system and the LAN to which they are connected.

A few voice mail vendors have enhanced their voice and fax mail systems to handle text messages and binary attachments. While this tightly coupled architecture is more reliable, it is not well-suited to a corporation that has already standardized on an e-mail system. In addition, it places considerable pressure on the unified messaging vendor to keep up with the feature race in each of the voice, fax, and e-mail messaging arenas.

Most unified messaging products use a loosely coupled architecture where the voice, fax, and e-mail systems run on distinct servers connected to a corporate LAN. The strength of this approach is that voice, fax, and e-mail messages can be presented in a single inbox without sacrificing the unique attributes of each messaging system, such as the high reliability of the voice mail system.

OPERATING COSTS
Operating costs include labor costs associated with administering the system as well as long-distance charges incurred both in the delivery of voice and fax messages and in the transmission of faxes.

On the surface, loosely coupled architectures seem to require that separate user accounts be maintained on each of the voice, fax, and e-mail messaging systems — an overhead that adds to the ongoing operating costs. While a tightly coupled architectural approach that provides a single administrative interface addresses this issue, it does so at the expense of product reliability or by resorting to a proprietary e-mail solution.

Disparate Directories
The problem of disparate directories is common to the messaging industry as a whole and has been addressed through the creation of an IETF (Internet Engineering Task Force) standard known as Lightweight Directory Access Protocol (LDAP). The LDAP protocol can be used for replicating directory information from a single source to different messaging servers. As accounts are added to the main LDAP server, the directories on all LDAP-compliant messaging servers are updated automatically. Unified messaging products from vendors who adopt this standard can be administered through a single interface without compromising product reliability or resorting to a proprietary email solution.

Long-Distance Charges
Another element of operating costs are long-distance charges that are incurred during message delivery between two systems. The conventional method of delivering a voice or a fax message from one system to another is for the originating system to place a telephone call to the receiving system and play out (or, in the case of a fax message, transmit) the message. If the majority of these deliveries require that long-distance calls be placed from one system to another, voice and fax message delivery can represent a significant operating cost.

E-mail systems already use IP networks as a toll-free transport for delivering e-mail messages. Since all voice and fax messages are essentially digital files stored on a messaging server, a number of unified messaging vendors have worked together to define a standard called Voice Profile for Internet Mail (VPIM). This protocol encapsulates voice and fax messages as a Multipurpose Internet Mail Extension (MIME) sub-type and transmits them as digital messages from one system to another over the Internet using the Standard Mail Transfer Protocol (SMTP). Messages from any VPIMcompliant system, from any manufacturer, can be delivered to any other VPIM-compliant system over an IP network, virtually eliminating long-distance charges.

An operating cost that is a characteristic of fax messaging systems are the long-distance charges associated with broadcasting faxes to a large number of fax machines. While the VPIM protocol bypasses the long-distance telephone network for the delivery of voice and fax messages from one server to another, a different bypass technique is needed to avoid fax broadcast toll charges since all but the most advanced fax machines are connected to the Public Switched Telephone Network and cannot be reached through an IP network.

Fax Toll Bypass
The most recent releases of fax messaging systems provide a fax toll bypass feature where each fax messaging system forms a node in a Point-ofPresence (POP) network. Before transmitting a fax, the unified messaging system identifies the least-cost hop-off node (i.e., the unified messaging system in the POP network from which the long-distance charges to the fax machine are lowest or non-existent). The originating system then transmits the fax over the IP network to the hop-off node which, in turn, places a low cost call to the fax machine. The costs associated with broadcasting faxes are significantly reduced in unified messaging systems that incorporate this feature.

USER ACCEPTANCE
User acceptance is critical for client/server products such as email systems that are purchased and maintained by a central IT department and used by all employees.

Some of the earliest unified messaging systems provided only proprietary clients that did not resemble any of the popular e-mail systems. This was due primarily to the fact that the first generation of Application Programming Interfaces (APIs) provided by email vendors were fairly rudimentary. While these proprietary unified messaging clients presented all three types of messages through a single custom inbox, some organizations which had already adopted a specific LAN-based email system, with a native e-mail client, were reluctant to invest in the additional employee training required to use a second custom client.

Many recently announced products have addressed this concern by using a more sophisticated API that allows unified messaging vendors to write software that hooks into a native email client, such as Microsoft Exchange, and transforms it into a powerful, yet intuitive, unified messaging client that can play voice messages and view fax messages using the same command structure and user interface that is used to display e-mail messages. While this approach is far more appealing to end users, different e-mail vendors have adopted different API models. This has forced each unified messaging vendor to develop a different set of hooks for each e-mail client, an expensive and tedious proposition for unified messaging vendors who wish to integrate with a wide range of e-mail clients.

A more practical alternative for unified messaging vendors is to comply with an e-mail server standard known as Internet Message Access Protocol (IMAP4). IMAP4 is a protocol for retrieving message envelopes and selectively downloading message bodies from a LAN-based messaging server. Messages stored on IMAP4-compliant voice and fax mail servers can be accessed and played (or viewed) by any IMAP4-compliant e-mail client. Only a modest amount of software is required to transform an IMAP4-compliant email client into a unified messaging client.

Furthermore, the list of IMAP4-compliant e-mail clients is growing steadily and, to date, includes over 50 email clients such as the upcoming release of Microsoft Outlook, Microsoft Outlook Express (the e-mail client in the Internet Explorer 4.0 Web browser suite), Netscape Messenger (the e-mail client in the Communicator Web browser suite), Lotus Notes 5.0, Novell Groupwise 5.2, and Qualcomm Eudora Pro 4.0. Each one of these IMAP4-compliant clients can present a unified view of voice, fax, and e-mail messages stored on multiple IMAP4-compliant servers located on the same corporate LAN.

MEDIA CONVERSION
Unified messaging systems can offer a range of media conversions including text-to-fax, text-to-speech, fax-totext, fax-to-speech, and even speech-totext and speech-to-fax. At present, these media conversion capabilities are at very different stages of maturity as they rely on leading-edge digital signal processing (DSP) technologies, such as natural sound speech synthesis, optical character and graphics recognition, and voice-dictation quality, speaker-independent, connected-word speech recognition. As the state-of-the-art in DSP technology continues to advance, all unified messaging products will eventually support a wide range of media conversion capabilities.

For better or worse, media conversion gets a lot of hype in the press and has become a considerable influencing factor in selecting a unified messaging system. Since almost all unified messaging vendors license the same underlying DSP technology from a handful of specialized suppliers, no one vendor can get more than a few months lead over their rivals. Furthermore, media conversion will work in all unified messaging product architectures. Consequently, the comparative advantage enjoyed by vendors who already provide one or two types of media conversion will be very short-lived and, in all probability, almost every unified messaging vendor will offer the same set of media conversion features within the next two years.

The two most prevalent forms of media conversion in today’s unified messaging products are text-to-fax and text-to-speech conversion. These two DSP technologies form the basis for forwarding e-mail to a fax machine anywhere in the world or playing email over the telephone. Both of these features cater primarily to business travelers who do not have ready access to a notebook computer or to a telephone jack for dialing into a corporate e-mail system. Unless there is a pressing need to support this type of business traveler, it is more important to select a unified messaging system that addresses all of the critical factors, even if it means waiting a few months for an upgrade that supports a particular form of media conversion.

SUMMARY
In order to make an informed selection decision regarding a unified messaging system, it is critical to understand the underlying product architecture. Those unified messaging systems that embrace existing and emerging email and Internet standards, such as LDAP, VPIM, and IMAP4, ensure that their voice mail and fax mail systems fit within an existing corporate IT infrastructure, providing all of the benefits of unified messaging, while maintaining the unique strengths of the individual voice mail, fax mail, and email messaging systems.

Lloyd Florence is director of multimedia messaging business development for Nortel (Northern Telecom), a leading global provider of digital network solutions. Symposium Messenger, Nortel’s unified messaging solution, integrates voice, fax, and e-mail into a single unified mailbox that can be viewed from a PC screen or accessed over a telephone. For more information on Nortel’s products and services, visit the company’s Web site at www.nortelnetworks.com