Today's information workers are constantly under deadlines. Regardless of the industry you manage, competitive and operational pressures put a premium on the ability to quickly access the correct information or people. Anything that reduces the time that is required to create, send, receive, or act on business information helps deal with these pressures.

Over the last few years, research has proven that the best rate of return comes from investments that raise the productivity of individual information workers and in tools to provide enterprise and team collaboration. Exchange 2007 Unified Messaging helps increase individual knowledge worker productivity by doing the following:

• Providing a single place where workers can access their information   When Exchange 2007 Unified Messaging delivers e-mail, voice mail, and faxes into users' Inboxes, they can access the information that they need immediately instead of constantly switching from one application to another. This lets users focus on the information instead of on managing the applications that they use to access their information.
  
• Keeping your mobile workforce highly connected   Exchange 2007 Unified Messaging enables remote users to stay connected by providing access to data from Outlook 2007, Outlook Web Access, Exchange ActiveSync, and the new Outlook Voice Access. This feature lets users manage their information from any kind of telephone. With Outlook Voice Access, users can perform tasks such as listening to e-mail messages and calendar appointments, forwarding and replying to e-mail messages, and updating or responding to meeting requests. Users can even use Outlook Voice Access to find messages from particular users, all by using either voice navigation or a standard touch-tone keypad.
  
• Including Exchange 2007 Unified Messaging auto attendants   Exchange 2007 Unified Messaging includes auto attendant capability to help both internal and external callers find the correct person quickly. The Unified Messaging auto attendant uses information from the Active Directory directory service to route calls both to specific employees and to roles or departments. For example, a caller who asks the auto attendant for "sales" can be routed to a specific extension, a hunt group, or a group voice mailbox.
  

Because Exchange 2007 provides these capabilities to existing messaging and collaboration systems, your information workers can access information more quickly and easily.

Analyst research indicates that organizations that widely deploy Internet Protocol-based communication systems may increase productivity by three hours or more per employee per week. This kind of gain comes directly from the improved access to and integration of voice mail, e-mail, and fax communications found in Exchange Server 2007 Unified Messaging.

Today, powerful browser-based clients such as Outlook Web Access are widely deployed for most organizations, virtual private networks (VPNs) are common, new mobile devices with high-speed wireless data access are becoming available everywhere, and technologies such as Outlook Anywhere provide access to Outlook data from almost any Windows-based computer that is connected to the Internet.

These trends are significant because many of today's organizations have a more mobile workforce than in the past. Users have become accustomed to working from remote locations. To be effective, information workers who work remotely must be able to access their e-mail, calendar, and contact data from multiple locations and devices, and have the contents of their inboxes consistently available (and synchronized) across multiple devices.

Exchange Server 2003 provided broad mobile access for e-mail and calendar data. However, two key communication types were missing from this model: voice mail and fax data. In most organizations, voice mail and fax data are tied to an individual telephone extension or fax machine. This requires that users switch communications modes, from computer to telephone and back again, for complete access to all their information. Exchange Server 2007 Unified Messaging provides a solution by making voice mail and fax messages available alongside existing e-mail, calendar, contact, and tasks. Users can choose the tools that work best for them. These include the following:

• Outlook Voice Access   Outlook Voice Access provides telephone access (with both touch-tone and speech recognition) to calendar, contact, and e-mail data from any telephone, anywhere in the world. This enables information workers who are working remotely to quickly obtain or send updates to their calendars, access their contact data, or receive new e-mail messages without requiring a portable computer, mobile device, or Web browser access.
  
• Outlook 2007   Outlook 2007 integrates voice mail as a first-class data type. The Outlook 2007 interface lets users sort, search, and prioritize voice mail messages together with their Exchange information. Additionally, users can play voice messages on their desk telephones and add notes to voice messages so that the contents of the message are indexed together with associated sender and date information. Outlook 2007 also provides complete support for user-configurable Exchange 2007 Unified Messaging options. These include configuring greetings and resetting PINs.
  
• Outlook Web Access for Exchange 2007   Outlook Web Access for Exchange 2007 enables users to access their voice and fax messages on a Web browser. Outlook Web Access provides access to many of the features of Outlook 2007 on a Web browser from the Internet. These include the ability to play back voice mail messages on the computer or the telephone and the ability to create and listen to audio notes.
  
• Exchange ActiveSync devices   Exchange ActiveSync devices are mobile devices that support the Exchange ActiveSync protocol. This protocol provides wireless and mobile access to Inbox data, including voice mail.
  

In addition to the client options listed here, Microsoft Entourage for Mac OS X lets users listen to voice mail messages if the necessary audio codecs are available on the host computer. This provides additional flexibility in environments where Mac OS X is deployed.

Helping users access their voice mail, fax, and e-mail messages from a variety of devices and client applications brings down barriers to efficiency. These barriers include requiring that users go to a physical fax machine or telephone to access their fax or voice mail data, or that they use a computer that has an Internet connection to read their e-mail messages.

Voice mail and telephony systems have delivered an extensive set of telephony capabilities directly to users. These capabilities include auto attendants that direct calls to the correct recipients, voice mail (including group messaging, transfer, and forwarding), call control features such as call forwarding and call routing, and conferencing. However, these features are implemented by the voice mail and Private Branch eXchange (PBX) hardware, which is typically distributed to the edges of the network topology. For example, companies with branch offices usually must maintain a separate voice mail system at each location. The costs of these systems can consume a significant part of communications budgets. The same is true of fax capabilities. Providing separate fax sending and receiving capabilities for your users increases the deployment and management costs for your messaging infrastructure.

The Exchange Server 2007 Unified Messaging features help address these problems by providing a solution in which voice mail and fax messages are centralized and stored on an organization's existing e-mail servers. Information is stored, backed up, and managed along with other business-critical messaging and collaboration data.

Currently, most companies have voice mail systems that use different types of voice mail servers and PBXs in multiple locations. This greatly adds to the management overhead and costs required for providing voice mail services to users. By enabling consolidation of voice mail services on Exchange 2007 Unified Messaging, Exchange Server 2007 cuts both the initial and ongoing costs of voice mail service by reducing the number of legacy voice mail systems that are required to provide every employee with voice mail. Additionally, because Exchange 2007 Unified Messaging combines the ability to receive faxes with the messaging and voice mail services, the costs of offering fax service really drop.

The following figure illustrates how Unified Messaging is used in an organization that has a single forest and multiple physical sites.

Because voice mail and fax data are combined on the organization’s Exchange servers, the same security and backup policies apply to voice mail, faxes, and conventional Exchange data. Journaling, compliance, and retention support are included and can be applied consistently across all data types. As an additional benefit, Exchange administrators can manage the Unified Messaging environment by using their existing skills and the familiar Microsoft management interfaces they already use. This further reduces costs by enabling your organization to take advantage of existing skills and capabilities.

The Unified Messaging server role handles interaction between telephone calls and the rest of the messaging system. The Unified Messaging server accepts call requests from the PBX, offers call answering for voice mail and fax calls, delivers Outlook Voice Access services to subscribers, records and plays back voice messages, receives faxes, and hosts the auto attendant. To understand how Exchange 2007 supports unified messaging and how it can be deployed to deliver the benefits described in this article, you must under the Unified Messaging server.

The Exchange 2007 Unified Messaging server role can communicate with two types of PBX hardware devices. Some PBX hardware devices, known as IP PBXs, directly implement Voice over IP (VoIP) capability. However, most PBXs do not directly provide VoIP services. Instead, they use legacy, proprietary, circuit-switched protocols to transport telephone traffic. For example, Time Division Multiplexing (TDM) is a circuit-switched method of transporting telephone traffic. These legacy PBXs require an IP gateway that translates between circuit-switched protocols and packet-based Internet protocols compatible with the VoIP network stack that exists in Exchange 2007 Unified Messaging.

When the PBX receives an inbound call, it is responsible for ringing the selected extension. If the call is not answered, the PBX uses its own call coverage configuration to determine where the call should go next. Assuming that the coverage configuration specifies transfer to Exchange 2007 Unified Messaging, the PBX routes the call from the original destination extension to the hunt group that is configured to point to Exchange 2007 Unified Messaging. For an IP PBX, the call is directly connected without a gateway. For legacy PBXs, the PBX reaches Exchange 2007 Unified Messaging through an IP gateway.

The IP gateway is responsible for converting the call data from circuit-switched to packet-switched protocols. Exchange 2007 Unified Messaging uses Session Initiation Protocol (SIP) for call setup and signaling, the Real-time Transport Protocol (RTP) for voice sessions, and the T.38 (fax over IP) protocol for fax data. Exchange supports (but does not require) using the Transport Layer Security (TLS) protocol to help secure and authenticate communications between the PBX or gateway and the Exchange Unified Messaging server.

Intel and AudioCodes offer gateway products that link Exchange Unified Messaging servers together with legacy PBX systems. For the latest information about the availability of IP gateways that are certified to work with Exchange Server 2007, see the Telephony Advisor for Exchange Server 2007 Web site.

You should understand what occurs when someone calls an Exchange Server 2007 Unified Messaging subscriber. The process is fairly straightforward, and the following section describes what actions the Unified Messaging server performs and also how it interacts with other components of the telephone and messaging systems.

Voice Calls

When a caller places a call, which is routed to the recipient's telephone by using the Public Switched Telephone Network (PSTN) or the organization's internal telephone lines, the call circuit is established. If the called number is a direct inward dial (DID) extension, the PBX will either ring the intended extension, or, if the dialed party is already on the telephone, the PBX will transfer the call to the pilot number of the Exchange Unified Messaging server. The protocol that is used to perform this transfer will depend on the type of PBX, as follows:

• If the PBX is an IP PBX, it establishes a session with the Unified Messaging server by using SIP. As soon as the session is set up, the live voice traffic is transferred by using RTP.
  
• If the PBX uses an IP gateway, the circuit-switched call data is sent to the IP gateway, which establishes a session with the Unified Messaging server by using SIP, and then translates the call and forwards the live voice data to the UM server by using RTP.
  

The original called party information is maintained as part of the supplementary signaling information when the call is transferred. When the call arrives at the Unified Messaging server, the called party information and the PBX source of the call are used to look up the user in Active Directory and retrieve their mailbox greeting. This is possible because each UM-enabled user has an associated extension. The Unified Messaging server retrieves the user’s welcome greeting, plays it, and records any message that the caller might want to leave.

Fax Messages

Fax message handling works in a similar method to voice call answering. By default, all users are enabled for fax. An organization can provide one fax number for all users, or an individual number for each user. Dedicated numbers will not actually ring any telephones. When a fax is sent to a dedicated number, the PBX transfers the call directly to the Unified Messaging hunt group. You can also set up a central fax number with a central fax Inbox for your whole organization.

Exchange 2007 Outlook Voice Access

When they access Outlook Voice Access, subscribers call the hunt group of the Unified Messaging system directly. There is no called party information in this case because the call was not redirected by the PBX from another called party. The Unified Messaging server answers these calls with the main menu, which asks the user to identify their mailbox number and lets them log on.

Auto Attendants in Exchange 2007 Unified Messaging

In telephony or Unified Messaging environments, an automated attendant or auto attendant menu system transfers callers to the extension of a user or department without the intervention of a receptionist or an operator. In many auto attendant systems, a receptionist or operator can be reached by pressing or saying zero. UM auto attendants are configured like voice users. In the PBX, a dedicated number is given to the auto attendant. This number is set up in the PBX to always redirect to Unified Messaging. When an incoming call arrives at the Unified Messaging server, the called party information is used by Unified Messaging to determine that the call is addressed to a particular auto attendant object. The greetings and menus of that auto attendant are then played to the caller.

When a caller leaves a message, the Unified Messaging server records the message. The server creates a new MIME-formatted SMTP message, with the audio message attached, and then sends it to the subscriber's mailbox. In practice, that means that the message is first sent to the Hub Transport server. The Hub Transport server can apply rules to the message to make sure that it complies with organizational policies. The Hub Transport server can store the message for later delivery if network problems prevent immediate delivery to the Mailbox server.

Messages are recorded by using the audio codec specified by the Exchange Unified Messaging server administrator. Exchange 2007 Unified Messaging supports the following three methods of encoding received audio:

• Uncompressed (16KB/sec) by using the G.711 PCM codec
  
• Compressed by using the industry-standard GSM 06.10 codec (approximately 1.6KB/sec)
  
• Compressed by using the built-in Windows Media (WMA) voice codec (approximately 1.1KB/sec)
  

WMA provides the best overall storage efficiency. Because a typical voice mail message size is around 30 seconds, Windows Media encoding is specified as the default audio codec. This is ideal, because voice data compressed by using the Windows Media codec can be played back on any computer that has an up-to-date version of Windows Media Player installed.

As soon as a voice mail message is delivered to the user's Inbox, the user can access the voice message by using a client such as Outlook 2007, Outlook Web Access for Exchange 2007, or Outlook Voice Access.

This same process is used for incoming faxes. However, the T.38 protocol is used to route the fax information to the Unified Message server. Additionally, the message in the user's Inbox will contains a Tagged Image File Format (TIFF) image of the fax contents.

Outlook Voice Access consists of the following two related interfaces:

• The Voice User Interface (VUI) enables subscribers to control Unified Messaging activities by using voice input.
  
• The Telephone User Interface (TUI) enables subscribers to control Unified Messaging actions by using dual tone multi-frequency (DTMF), also known as touch-tone input.
  

For Exchange 2007, the VUI is supported in English (United States, United Kingdom, and Australia) and the TUI is available in English (United States), English (United Kingdom), French (France), French (Canada), German, Japanese, Italian, Spanish (Spain), Spanish (Latin America), Portuguese (Brazil), Korean, Mandarin (China), Mandarin (Taiwan), Dutch, and English (Australia).

When a subscriber calls the Outlook Voice Access number, their call is routed by the PBX to Exchange Unified Messaging. As soon as the subscriber is connected to the Unified Messaging server, the subscriber authenticates by using DTMF. Outlook Voice Access enables the subscriber to listen to voice messages, play e-mail messages, listen to calendar appointments, accept or reject meeting requests, send "I’ll be late" messages to meeting participants, retrieve contact information, connect to contacts, or search the directory.

Exchange 2007 Unified Messaging protects a user's voice mail access by using PINs. Every UM-enabled mailbox has a PIN that is separate from the user’s Active Directory account password. The Unified Messaging PIN is stored as an encrypted attribute of the user’s Active Directory account object.

When a user mailbox is enabled for Unified Messaging, the administrator specifies a PIN. Users can reset their own PINs through Outlook Web Access or through the Outlook Voice Access interface. Administrators can set policies for PIN length and expiration and different PIN policies can be applied to different groups of users.

Exchange 2007 Unified Messaging supports two related types of consolidation, as follows:

• Site consolidation reduces the number of sites that have their own dedicated voice mail systems.
  
• Server consolidation (also known as system consolidation) reduces the number of voice mail systems that are required to provide service to a given number of subscribers.
  

These two types of consolidation can occur together or separately. The exact mix of site and server consolidation in your organization will depend on how many voice mail systems you have, where they are located, and how many subscribers they host. However, because Exchange 2007 Unified Messaging uses standard Internet protocols for signaling and voice transport, you can selectively replace individual voice mail systems regardless of where they are located.