February 1999

Protocols Push Universal Messaging Out of the Waiting Zone

BY LAURENCE J. FROMM

Unified messaging has been long anticipated. Now the ingredients are finally in place to make messaging not just unified, but universal. The voice profile for Internet messaging (VPIM) standard -- a messaging protocol that will let disparate voice messaging systems exchange voice mail over the Internet -- combines with a directory service based on the lightweight directory access protocol (LDAP) standard. Together, these two standards are poised to usher in a new era of universal multimedia message management.

BEHIND THE UNIFIED INBOX
By now, screen shots of a unified messaging system are familiar. In fact, in some quarters, icons in a client's inbox representing e-mail, voice mail, or fax symbolize the very definition of unified messaging. There is no doubt the explosive growth of e-mail has fueled the interest for a common inbox. But the benefits of unification come more from universal messaging than from simply unifying messages on the desktop.

Essentially, universal messaging means transparently using any type of existing or future access device to interact with messaging systems. It also means the user has a transparent interface -- currently a graphical user interface (GUI) or telephone user interface (TUI) -- to the message being deposited or retrieved. The more ubiquitous the device, the more important it is as a user terminal. The most universal device of all is the telephone. So when we evaluate universal messaging systems, it is at least as important to look at the components that interweave telephonic messaging as it is to consider messages on the desktop.

A PARALLEL EVOLUTION
One of the most significant impacts of the digital revolution on the telecommunications industry is that customers have come to expect more from technology service providers. Telecommunications vendors and service providers have responded by embracing open systems technologies to keep up with the rate of change consumers demand. Advanced intelligent networks (AINs), Signaling System 7 (SS7), computer telephony integration (CTI) links, and open switches are all manifestations of the trend toward open systems. And the proliferation of TCP/IP networks has added still another dimension to communications.

The parallels between open client/server computing in the data world and the move away from monolithic proprietary systems in the telephony world do not end there. E-mail is the undisputed killer application on the data networking side, and SMTP and MIME were crucial to its success. There is a similar opportunity in the voice and fax messaging realm. VPIM, coupled with a standard LDAP-based directory service, can unify disparate voice messaging systems -- enabling universal multimedia message management. It is also important to note that moving voice and fax messages back and forth on the data network leads to tangible cost savings.

AVOIDING VOICE MAIL JAIL
How does VPIM enable a killer messaging application? Again, the precedent is e-mail, which has made intentional messaging a model for business and social communication. For evidence of just how widespread e-mail use really is for critical business communication, look at the Microsoft antitrust trial.

At first glance, the productivity lost by having to dial a number may not seem like such a big deal -- waiting through a painfully long number of rings, then a long greeting. But by some estimates, nearly 60 percent of business calls end up in voice mail "jail." That amounts to a lot of time waiting to get dumped into someone's voice mailbox, not to mention the instances where a simple "Let's reschedule our 4 o'clock…" turns into, "And another thing -- that upgrade you sold me last month has crashed the whole system…." Wouldn't it be easier to just compose a short voice message and forward it to one or more destinations accessible by the recipients from both the telephone and the desktop?

VPIM, coupled with LDAP, does two key things. First, it defines a common format for exchanging voice and fax messages among disparate messaging servers. Second, it takes advantage of the ubiquity of telephones by enabling a compose-and-forward scheme for voice messages. It is just as easy to whip up a multirecipient voice message -- return address and all -- as it is to send e-mail. Plus, the voice message has the advantage of coming complete with the intonations and inflections that make speech so comprehensible. Fax messages can also be distributed, forwarded, or received in the specified VPIM format, potentially saving much of the estimated $40 billion companies spend each year in long-distance fax charges.

THE VPIM STANDARD
VPIM is a legacy of AMIS-D, an International Telecommunications Union (ITU) standard for interchanging digital messages between proprietary voice mail servers. VPIM builds on SMTP and MIME standards for e-mail interchange to allow standardized exchange of voice and fax messages among servers. At the core of VPIM is the G.726 voice encoding scheme, which calls for a MIME-encoded message of 320 KB per minute of speech via SMTP, or 240 KB with the binary SMTP service extension.

VPIM can be implemented in two ways to network islands of messaging systems. Older legacy systems need to be connected to a VPIM/SMTP gateway that encodes individual voice or fax messages into VPIM-based packets that can be transported to other parts of the LAN or WAN. Alternatively, users can demand that voice mail vendors comply with the VPIM standard and include the VPIM/SMTP native within the application. In either case, the VPIM conversion allows voice messages to be abstracted in a standard way for transport over the packet network.

VPIM also makes provisions for envelope- and header-type information, much like e-mail. VPIM's business card extensions allow each message to encapsulate a name, phone number, e-mail, spoken name, and VPIM address. With specific fields for addressing information, it's possible to automatically map phone numbers or e-mail addresses to VPIM identifiers so users can transparently look up contacts and group mailing lists -- much like they do (you guessed it) in e-mail. This is where the use of a shared X.500 directory and LDAP comes into the picture.

X.500/LDAP PROVIDE DIRECTIONS
While VPIM spells out the format of voice and fax messages, shared X.500 directories and LDAP help direct those messages. Much like the rollout of VPIM-enabled messaging systems, LDAP directories can be implemented at various stages. Depending on the messaging needs of an organization or user community, shared LDAP directories can reside within a single application domain or a larger corporate domain, or they can straddle corporate boundaries. In other words, the requirements of the user community and the owners of the affected network segments determine the degree to which the messaging system is made public.

Ideally, VPIM messages and recipients should be accessible across the widest possible domain. This will, however, require a significant effort on the part of equipment vendors and service providers. On the other hand, it's possible to define finite user communities -- for example, everyone represented by a single corporation and its trading partners -- and make them serviceable with strategically-placed LDAP directories. The result is seamless interchange of voice and fax messages. Here, the tangible savings from reducing circuit-switched voice and fax mail traffic can help offset the cost of upgrading to this more productive messaging environment.

While VPIM dictates a standard exchange of voice and fax messages between servers, it imposes no such standards between the server and the desktop client. Client application vendors are free to choose how to VPIM-enable the client. Most likely, vendors will integrate a VPIM encoding and decoding mechanism, along with POP and IMAP4, for interacting with the messaging server.

THE ERA OF OPEN COMMUNICATIONS
Combining VPIM and LDAP with today's open data networking makes it possible to build that all-elusive universal messaging network. Increasingly, voice networks will have to adapt to a data-centric model built on the concept of interoperability. Standards like VPIM, X.500, and LDAP allow interoperability within voice networks, as well as interoperability with the general communication network. Soon, voice and data will become indistinguishable, sharing a common infrastructure.

The users and owners of those networks dictate the evolution -- not revolution -- of the converged networks. Clearly, LAN-based open communications platforms are the first step in that evolution. Open hardware and software standards -- such as H.100, S.100, TAPI, H.323, T.38, and a host of others, have made building open communications networks in the enterprise a reality. Carrying that momentum further, standards such as TCP/IP, SMTP, and MIME -- and now VPIM and LDAP -- have enabled the level of interoperability to extend beyond the isolation of enterprise networks.

Laurence J. Fromm is vice president, new business development for Dialogic Corporation. Dialogic is a leading manufacturer of high-performance, standards-based computer telephony components. Dialogic products are used in fax, data, voice recognition, speech synthesis, and call center management CT applications. The company is headquartered in Parsippany, New Jersey, with regional headquarters in Tokyo and Brussels, and sales offices worldwide. For more information, visit the Dialogic Web site at www.dialogic.com.