Unified messaging is a simple concept: All your messages--voice, email, fax, data (such as documents)--go to one inbox. Everything in your inbox is accessible from your desktop PC, any telephone, or your laptop computer. From your desktop or a Web browser anywhere, you can review these messages, which appear as single-line summaries on your inbox screen. Click the message you want, and you see or hear the message, no matter what medium the message is in. Or using any telephone, you can hear your voice messages, forward received faxes to the nearest fax machine, or even have selected email messages faxed or read to you.

Such messaging solutions are readily available today. Recognizing that work is an activity, not a location, unified messaging vendors offer universal access to all your message types.

Unified messaging offers significant benefits. It simplifies communication and saves time. You no longer need to run separate programs from your desktop to get your email, voice mail, and faxes. Using a screen to access your voice mail is more efficient than pressing buttons on your phone to wade though an unseen list of voice messages.

Integrated and Unified Messaging Defined
Unified messaging describes generic universal access to one multimedia mailbox. Integrated messaging refers to an architecturally different implementation of the unified messaging concept. Each technology has benefits and challenges.

Unified messaging systems present messages to users through one interface, but you maintain all message types and user directories in one set of data stores. As shown in Figure 1, although the underlying special interface cards for receiving and sending the fax, voice, and email messages can be in separate server systems, all messages point to the same storage database and use common message storage resources. Also, only one copy of each message exists, no matter what the message type.

Integrated messaging systems present messages to users with one user interface (usually the email client) that displays one virtual inbox that references different message locations, or stores, for each medium. The enabling technologies for this approach are open-messaging standards and their APIs such as Messaging API (MAPI) and Vendor Independent Messaging (VIM).

As Figure 2 shows, independent servers manage email, voice, and fax message types; more important, the underlying server databases are independent. However, this scenario often requires that you maintain a separate copy of the non-email messages on the email server, too. Also, the user directories are separate; you store and maintain each directory on its respective server.

The immediately obvious benefit of unified over integrated messaging is a single point of administration and control for the system. Maintaining one user directory instead of three or more can be a significant administrative advantage in large enterprises.

But deciding which messaging solution is best is not easy. One advantage of integrated messaging over the unified messaging is that you can make disparate legacy message servers appear as one with the appropriate client and accompanying software. This solution can be less costly than a unified messaging solution because corporations that already have fax and email servers don't have to replace them; the corporations can just add a voice mail server and special software to enhance the email client to display voice messages. In this example, the client has to synchronize the different messages, message storage locations, and user directories for each message server.

Basic Architecture
To construct a unified messaging system (as shown in Figure 3), you must assemble several system components, including email, voice, and fax servers and the corporate Public Branch eXchange (PBX) and LAN-connected workstations. The voice server contains the physical interface between the corporate LAN and the internal PBX; the voice server lets telephone callers dial in from outside the company or from their internal extensions (if they have workstations without multimedia capabilities) and create and retrieve voice mail messages. Fax servers contain the necessary fax cards and software for sending and receiving faxes over phone lines.

Phone lines connect to both the voice and fax server platforms (in some cases, one voice and fax server platform) so the servers can handle incoming and outgoing calls. Most often, the PBX lets you access the voice and fax lines as extensions inside the company and by a direct Public Switched Telephone Network (PSTN) for outside calls.

You can access message objects in your unified messaging inbox via a GUI or a telephone user interface (TUI--that is, calling from any push-button telephone). The GUI displays a list of messages on the screen; an icon next to each message depicts the medium. You point and click to access the message you want. The GUI can be Web-based, making message retrieval possible via any intranet or Internet connection.

The unified messaging TUI builds on its voice mail roots to let telephone callers retrieve different message types. For example, you log on to your inbox using the TUI, and the system announces, "Good morning, Wendy. You have 13 voice mail messages, 6 faxes, and 12 email messages. To listen to your voice mail messages, press 1; to retrieve your faxes, press 2; or to listen to your email messages, press 3." This is powerful mixed-media technology at work.

For business travelers, the ability to connect at all times to your flow of messages through a TUI-based interface is a long-sought solution. Harnessing dramatically improved technologies such as text-to-speech for email reading, unified messaging can finally deliver on the promise of a single point of access to all message types.

Ideal Features for Users
So what makes for an ideal unified--in the generic sense--messaging system and architecture? The answer for users is a common GUI, Web access, external email, the ability to receive private faxes, TUI access, and flexible message notification.

Common GUI front end. You can run one program (such as Microsoft Exchange) on your desktop to see all your messages in all media. You manage your personal mail profile from the GUI and define how to handle message notification and other processes. You usually set up your preferences through extensions to existing email clients such as Microsoft Exchange, Novell Groupwise, or Lotus Notes.

Web access front end. You can use any Web browser to access mail. Or, you can perform other functions you can do with your GUI front end.

Send messages to people not on your system. You can send all message types from your GUI front-end program to people reachable by email, even if they do not have a mailbox on your unified messaging system. For example, you can send a voice or a fax message as an email attachment to anyone, anywhere, who is running Microsoft Exchange. The recipient clicks the attachment, and the appropriate device plays or displays the message.

Receive private faxes. You can receive faxes directly into your personal mailbox. You can specify a unique fax telephone number in your fax server. The unique number cues the fax server to transfer the fax to your mailbox through a feature called Direct Inward Dialing (DID).

Or you can let outside callers call from their fax machine handset into the voice system. From there, they select your mailbox number, then press the fax machine's Send button to directly deposit a fax into your inbox. This private fax method is an alternative to receiving your faxes at a public fax machine and manually routing or copying them.

TUI access. You can access all message types from any touch-tone telephone. You can hear voice messages, listen to email messages, and forward faxes to the nearest fax machine.

Flexible message notification. You can receive notification of pending mailbox messages wherever you are. With multiple message-type capability, the ideal system lets you configure any medium as your primary notification method and lets you specify whether urgent-only or all messages initiate notification. For example, you can tell the system to call your pager between 9:00 am and 5:00 pm when you receive new messages; at other times, the system can send you a fax or email message to notify you of your waiting messages.

Ideal Features for Administrators
The features that administrators need go beyond the list of what users want in a unified messaging system. Administrators want replication, centralized management tools, one user directory, integral security, an easy-to-use GUI, and a scalable architecture.

Replication. The system automatically replicates user directory entries and changes to networked and remote messaging servers. You can replicate messaging objects (e.g., voice, email) according to site messaging server profiles.

Centralized management tools. You can monitor and manage all mailboxes through one GUI. And you can easily add or delete subscribers and move subscribers from one domain or messaging server to another.

One user directory. You can maintain one directory entry for all mailbox message types. This feature lets you run only one program when you need to add, move, or delete users. Typically, administrators can maintain this directory as part of either the email server or the LAN operating system.

Integral security. Administrators can set specific user rights according to the type of message (voice, fax, email, etc.). You can require an additional password, for example, when you transfer faxes to an offsite fax machine. The system would implement all security features as extensions of Windows NT's underlying security layer.

Easy-to-use GUI. The unified messaging front end requires little training. Users already familiar with Exchange will feel familiar with Exchange-based systems. For PCs with multimedia capabilities, voice-message audio plays or records from a local sound card. For PCs without sound cards, the unified messaging system calls any local phone extension or number you specify and uses the phone connection as a virtual sound card.

Scalable architecture. You can add new mailboxes, new departments, and even new message servers easily, without replacing what already exists. With NT-based systems, you can implement multiprocessor or multiuser solutions to meet performance targets.

Waiting for the Desktop Standard
Integrated messaging products have been around for nearly five years, but until recently they have not raised significant enterprise interest. Two early integrated messaging pioneers were Active Voice and Applied Voice Technology (AVT). Both shipped products in late 1992 and 1993.

Users of these new applications saw them as an efficient way to view voice and email messages on the same screen; the applications were impressive accomplishments at the time. Other voice mail vendors followed the two companies' lead in offering integrated messaging solutions, and the race was on to grab enterprise desktop market share.

But sales of integrated messaging never fulfilled early expectations. Vendors ended up primarily selling their standalone voice mail systems. Something wasn't quite right.

One important reason for enterprise resistance was the requirement that users give up their email client in favor of the proprietary messaging client that the voice mail companies supplied. The early integrated-messaging vendors figured that the benefits of a common GUI to view both email and voice mail messages was enough to convince enterprises to throw out their existing email systems.

Users didn't like this approach because the new desktop clients were different and often lacked some familiar features of their standard email program. Administrators didn't like this approach because it meant splitting the company into two groups: people who had the corporate standard email program and those with the integrated messaging front end. That dual system meant extra training, extra support, and extra cost.

Enter computer telephony (CT) rule #1: CT systems enjoy the highest level of acceptance when they adapt to their network and telephone surroundings rather than replace them. So the next big issue for enterprise acceptance was which email client was flexible enough to assimilate new integrated/unified messaging features?

Exchange to the Rescue
Exchange has influenced the acceptance of integrated and unified messaging in the enterprise. Exchange is rapidly becoming the standard as a messaging front end; most major voice mail vendors have declared their intentions to support integrated messaging under Exchange. MAPI and the Exchange client extensions make this support possible.

Not all industry leaders in unified messaging, though, are singing an Exchange-only tune. Vendors such as AVT and CallWare Technologies also support Lotus Notes and Novell Groupwise as desktop email clients for their integrated messaging solutions. Octel Communications intends to support other email platforms, too, as part of its unified messaging strategy.

But vendors express excitement and hope for Exchange- and Microsoft Outlook-based solutions for continued enterprise growth of unified messaging. (Outlook is the new desktop information manager that is part of Microsoft's Office 97 Suite.) Exchange 5.0, Outlook, and NT's next-generation Directory Services promise new features to make single-directory unified messaging systems easier to implement than before. As a result, more vendors can offer products that follow the true unified model with Exchange Server, storing different message types in one server system.

Some Unified Messaging Products
Let's briefly look at some integrated and unified messaging products from some key vendors. For more detailed information and product demos, you can go to the vendors' home pages.

Active Voice. Active Voice says the company was first to show an integrated messaging product, TeLANophy, in fall 1992. Active Voice, like AVT, has been responsible for much of the pioneering development and market work.

Active Voice announced ViewMail for Microsoft Messaging, which offers a full set of integrated messaging capabilities. This product works with both Exchange and Outlook clients. ViewMail for Microsoft Messaging offers voice, fax, and email support that lets you send voice mail messages to anyone reachable by Exchange, even if the recipient does not have an active account on any voice mail system. Active Voice also has integrated messaging support for Lotus Notes and Groupwise, but the company believes strongly that Outlook will win as the best possible unified messaging platform and client interface for the enterprise.

Active Voice's leaders say they will offer both integrated and unified messaging solutions and let their customers choose which is best for them. The company is currently working on its next-generation Exchange-based true unified messaging product.

Applied Voice Technologies. AVT has produced an integrated messaging solution since fall 1993. AVT now successfully ships thousands of copies a year of CallXpress3.

CallXpress3 offers both TUI and single-screen GUI (the latter shown in Screen 1) interfaces to messages in a unified inbox model, allowing support of voice, fax, and email message types. CallXpress3 offers message platform support for both Exchange and Groupwise. AVT says that this year, it will introduce a server-based (true unified) messaging system that will run under both Exchange and Groupwise.

AVT also recently announced CallXpressNT, a fourth-generation NT-based computer telephony server. CallXpressNT offers a scalable solution that will interoperate with other Microsoft Back Office products, such as SNA Server and SQL Server.

CallWare Technologies. CallWare Technologies started into unified messaging a few years ago as a Novell-centric system, then took the Exchange road after refining its voice mail product. CallWare 5.2 messaging server and the ViewPoint 5.2 GUI offer a rich set of integrated messaging capabilities. CallWare Technologies now offers integrated email client support for Exchange, Lotus Notes, and Groupwise. Screen 2 displays CallWare's Groupwise messaging client. ViewPoint offers integrated voice, fax, and email support from the messaging client. ViewPoint lets you attach a voice mail message to an email sent over the Internet.

CallWare has amassed a great deal of experience in deploying integrated messaging solutions and has developed a good product that has matured through field trials and customer fine-tuning. Features such as logging all mailbox message activity and making it available in reports simplifies your job when you have to track the status of a message.

Octel Communications. Octel is the world's largest voice mail vendor, and one of its primary targets is the enterprise. Not surprisingly, the company is working on unified messaging solutions. Octel has already announced Unified Messenger, the industry's first true unified messaging system to use Exchange as the messaging server platform. Screen 3 shows the in-box in Octel's Unified Messenger. The first release will add voice mail support to Exchange Server, and a future release will support fax as another message type.

Unified Messenger was an aggressive project, and Octel is clearly proud of what the company has accomplished. Unified Messenger adds a tab to the Exchange user directory to handle user-specific information for the voice server features. The product extends NT's security layer to manage the password information necessary to add the voice and fax message types. The product has no new administration programs, only extensions of existing ones.

Octel says one challenge in implementing a true unified messaging system was dealing with earlier-generation APIs that didn't work in a multitasking environment. A lack of message data-streaming protocols made getting adequate message retrieval performance impossible. Microsoft Exchange solved both problems, and the system works well, according to Octel. In the future, Octel's Unified Messenger will add support for Lotus Notes and Internet's IMAP standard, but Exchange is the anchor offering.

A New Era
Today's commercially available integrated messaging solutions have advanced from experimental technology to the real thing in the past few years. The industry is at the threshold of a new era of true unified messaging platforms running on NT and based on Exchange and Outlook. Now is the time to explore this technology. In the near future, unified messaging is destined to become another essential communications building block in the enterprise.

See also The Debate: Integrated Vs. Unified Messaging