Unified Messenger is based on the client/server architecture of Microsoft Exchange and has the capacity and intelligence to serve thousands of users with the necessary high performance and reliability. Architectural components include the Exchange Server, the Unified Messenger Server, LAN and PBX connections, personal computer clients and, if desired, gateways to outside networks or the Internet.

EXCHANGE SERVER

The Exchange Server is the repository for all user messages. Multiple Exchange Servers configured on a network each contain a logical group of user mailboxes and a copy of the directory. Message Transfer Agents (MTAs) transport messages between servers over a variety of LAN or WAN connections.

Key components of the Exchange Server include:

• All user mailboxes—everyone's mailbox resides on an Exchange Server.
• All mailbox content—voice, and e-mail messages and, in the future, fax and other documents are all stored in an Exchange mailbox. The Exchange server stores messages as objects, as file attachments, or as simple text messages. Compressed voice and fax messages are stored here for playback, retrieval or transport.
• Directory—the Exchange Server directory manages addressing for Exchange and Unified Messenger. System managers need only make changes once—any change in one Exchange server directory is automatically replicated to all other directories in the network. Directories can also accommodate addressing for external destinations—fax numbers or e-mail addresses for customers, vendors, independent contractors, business partners, etc.
• Message Transfer Agent (MTA)—the Exchange software that transports messages between mailboxes and between Exchange servers. MTA also updates and replicates directories.

UNIFIED MESSENGER SERVER

The Unified Messenger Server connects the LAN and telephone networks and acts as a bridge to provide transparent management of voice and fax data stored on the Exchange Server. The Unified Messenger Server records the message and sends it to the user's mailbox on the Exchange Server. No messages are stored on the Unified Messenger Server.

The Unified Messenger Sever is also a high-performance LAN server operating on Microsoft's Windows NT. It is the integral link between the LAN and telephone network. When managing voice messages, the Unified Messenger Server's role is to:

• Play and record voice messages.
• Provide telephone answering service for individual users.
• Compress and decompress audio in real-time for storage and retrieval on the Exchange Server.
• Interpret DTMF for mailbox manipulation and control.
• Perform text-to-speech conversion for audio playback of text such as e-mail.
• Exchange messages with users on voice messaging systems and other e-mail systems.

Playing back a message over the telephone results in the message envelope (subject and addressing information) being moved to the Unified Messenger Server and played. The voice data is then read from the Exchange Server, using a stream interface, decompressed and played in real-time using specific voice processing resources.

Voice messages can also be recorded and played back on a multimedia equipped PC using Unified Messenger client software integrated with the Exchange client.

Unified Messenger Server Connections
As noted earlier, Unified Messenger connections include both LAN interfaces and PBX integrations. Located in the Unified Messenger Server are Rhetorex cards equipped with DSP resources to capture and compress voice data as well as to detect DTMF input.

In addition, the Unified Messenger Server includes specialized connections to the PBX (referred to as PBX integration). The PBX integration provides key information about the calls as they are routed to the Unified Messenger Server. The information includes: who the call was originally intended for (called party), who placed the call (calling party) and what caused the call to be routed (no answer, busy).

Contrary to LAN interfaces which are based on industry standards, PBX integration interfaces are developed by PBX vendors and are unique to each vendor's PBX line or even each model within a PBX line. Having a reliable, efficient and effective PBX integration is critical to the operation of a voice messaging system and equally important to a unified messaging system. Lucent has extensive experience in developing PBX integrations, and as a result is able to provide support for a wide range of PBX integrations.

Clients
In an implementation of Unified Messenger, Exchange client software resides on each user's PC. It facilitates the sending and receiving of data between the client PC and the Exchange server, and manages the display of all messages contained in the user's Exchange mailbox.

Unified Messenger client software interacts with the Exchange client to facilitate and control the recording and playback of voice messages. Unified Messenger software is supported on the Outlook 97/98/2000, Exchange 5.0 client with Windows95/98 or WindowsNT 4.0 (or above).

The telephone is also a client for Unified Messenger. Requiring no special connections or software, any telephone is able to be used to record and listen to voice and e-mail messages. It also serves as an input device allowing the user to act on messages—replying to or forwarding messages, storing messages, or deleting them. Lucent has extensive experience in developing telephone user interfaces that enable users to gain maximum productivity from the messaging process.