Finding Unified Architectural Diversity By David A. Zimmer   A unified messaging architecture attempts to wed voice-mail, e-mail, directories and other productivity tools into one cohesive system without compromising any single tool's functionality. Voice messages, faxes, e-mail and forms are stored in one mailbox that can be accessed by telephone, PC or other devices, such as two-way pagers. This variety of messaging-access methods provides flexibility: You can use a telephone while at the airport and your PC while in the office, for example. Several iterations of unified messaging have been attempted, but only recently have products been introduced that provide full integration between media types and access devices. We evaluated solutions from Active Voice Corp., Applied Voice Technology, Centigram Communications Corp., Digital Sound Corp., Lucent Technologies and Octel Communications Corp. in an effort to describe the various architectures available and any product constraints on design decisions. An und erstanding of the issues--such as where to store your messages and how or if you should synchronize them--will help you determine the best options for your organization. Unified messaging products fall within four architectural categories: voicemail-centric, with messages residing in the voice mail store; e-mail-centric, with messages residing in the e-mail store; client integrated, using client software to integrate the media; and server integrated, using synchronization of various media mailboxes. Typically, a vendor's voicemail product will dictate the unifying architecture used. Installations dependent on legacy systems--or those willing to incur the expense of changing products--can let thei r needs dictate the proper architecture. All told, those with many databases to be included in the unified mailbox will benefit from an integrated approach--such as a server synchronization approach. But for those concerned with maintenance, generally a single message store provides easier administration. Same Book, Different Pages There are no standards for unified messaging. As a result, all solutions are proprietary or de facto standards. Octel's Unified Messenger uses Microsoft Corp.'s Messaging Application Programming Interface (MAPI) to place messages in Microsoft Exchange. Active Voice, Centigram and Lucent say they also will ship MAPI-supported products. But, for now, standards still are needed for voice compression, voice recording and playback, directory interaction and calendaring. Most companies have voice and e-mail systems in place, so vendors are building products to bridge these systems. These products integrate the message stores at the client or in the server. Lucent joined with Lotus Development Corp. to leverage their common base of customers and the pair built a synchronizer to keep the two message stores updated, for example. In contrast, Octel built Unified Messenger from the ground up. This program does not support the embedded infrastructure directly, so to maintain a custom er's investment, Octel uses OctelNet. OctelNet converts text-based e-mail to speech that can be returned to the originator's legacy voice mailbox or the originator's legacy e-mail account, depending on system configurations. Design Differences Unified messaging architectures fall into two categories: single physical message stores and multiple message stores. The goal, regardless of architecture, is to make the message store appear as a single store to the user. Four different architectures derive from the two categories. Voicemail-centric systems, such as Boston Technology's AccessWEB, store all messages in the voicemail store. With a telephone or PC interface software, users c an listen to the number of voice, fax and e-mail messages in their mailbox. They then can delete or move a message to another folder, reply to originator (it will be addressed in the manner appropriate for the return path), or forward it to another recipient. The e-mail component of this system is used simply as a transfer agent between external e-mail systems and the voicemail server (see "Voicemail-Centric Messaging," at right). Voicemail-centric architecture eliminates any latency issues or performance affects from the user's perspective because of the single store.

QoS: Crating Ine quality in an Equal World by Chris Lewis Updated May 12, 1997