Messaging refers to non-real-time communications by way of voice mail, e-mail, fax, and the like. Of these, voice messaging and fax have traditionally been provided by voice networks and e-mail by the Internet. Until recently, each form of messaging required separate storage, access, and management; neither the applications nor the specialized devices worked with each other.
Unified messaging is positioned to eliminate the boundaries across these different forms of messaging. As a result, users can create, send, and retrieve any type of message with any type of terminal anytime, anywhere (Figure 1).
Figure 1: Unified messaging.
(Courtesy of Jackie Orr.)
Users are given access to any type of message from a number of devices that themselves belong to different types of networks. They have the following options for retrieving messages:
§ Receiving notification of incoming messages (regardless of type) on a combination of devices such as telephone, PC, and personal digital assistant (PDA).
§ Using a PC (or PDA) to retrieve voice-mail messages. Depending on the technology and device available, this option provides two further possibilities:
1. Playing the messages on the PC (or PDA), if it is equipped with a speaker.
2. Reading the voice messages (converted to text) on the PC (or PDA).
§ Using a telephone to retrieve e-mail messages. The e-mail messages can be delivered to the user as voice-mail messages with the help of the text-to-speech technology. Alternatively, the messages can be delivered via facsimile to a fax machine that the user specifies, after the user listens to the converted message headers.
§ Using a PC (or PDA) to retrieve fax messages, or requesting that the fax messages be delivered to a specific fax machine.
§ Using a telephone to retrieve fax messages and listen to them (here the messages are first converted to text—involving a character recognition application—and then to speech), or requesting that the fax messages be delivered to a specific fax machine.
The user has various options for sending messages as well. You can mix the means for both creating and delivering messages. For example, the user can create a voice message using the telephone over the PSTN and have the voice message delivered to the recipient as a voice attachment (or just as a plaintext message with the help of the voice-to-text technology) via e-mail over the Internet.
Behind unified messaging is the concept of the universal mailbox (see Figure 2), which holds messages of all types in a single logical location. With a universal mailbox, the user no longer needs to be concerned with the location of messages. In addition, the user is given numerous options for handling messages, regardless of their format and means of access. For example, the messages can be:
§ Sorted by using any part of the header information (such as subject, date, sender, length, and priority) as the key.
§ Selected from a list of common operations (such as reply, forward, save, delete, skip, rewind, and fast-forward).
§ Stored in files, which can be further organized into folders.
§ Filtered according to priority, subject, sender, and so on.
§ Mixed with other messages (possibly of various types, so an audio message and a spreadsheet can be combined into one message) and sent to another user.
Today, unified messaging operations are most effectively performed on the computer. As the limited (and limiting) capabilities of the telephone keypad are being augmented by voice-controlled applications, telephones are on their way to becoming as effective.
A closer look at unified messaging reveals its essence: the use of the e-mail paradigm by voice mail. The universal mailbox is connected to networks of different types and acts as a voice portal for voice-controlled services.
The immediate improvement in services that has resulted from the application of the e-mail paradigm is best illustrated in a relatively new voice messaging application called call sender with rebound. An annoying feature of yesterday’s voice mail was that you could not return a call pertinent to a particular message without leaving the mailbox. You had to either write down on a piece of paper all the numbers while listening to all the messages (and risk forgetting in the process what some of the calls to be returned were about) or keep calling the mailbox back after each call returned. Clearly, this is not how e-mail works; e-mail is more flexible and user friendly. The call sender with rebound feature available in today’s top products works just like e-mail: It allows the recipient of the message to call back and, after having completed the call, to return to retrieving the messages starting just at the point where he or she left off. The procedure of calling back (using traditional telephone) was also adopted from the e-mail paradigm: You can call back by pushing a single button on a telephone keypad or giving a voice command. In addition, the return addresses of voice messages delivered by the PSTN (that is, telephone numbers) can be stored in and retrieved for redial from personal address books. Similarly, the voice confirmation of (voice) message delivery is a very convenient e-mail-like feature, and so are the abilities to send messages to groups and to specify delivery options.
Another interesting application called reply-to-telephone answering enables messaging replies to telephone callers. Through access to an IN database, the contact options of the calling party are captured and presented to the called party, who has a choice of returning a call, sending a voice message to the caller’s voice mailbox, or sending a voice message via a store-and-forward network.
To access voice messaging from the computer, the visual mail application, convenient for small-office/home-office (SOHO) subscribers, provides end users with the ability to see (and edit) complete lists of their incoming or stored voice-mail and fax messages. The messages can be replied to by using the microphone of a multimedia computer; they can be forwarded, copied, and so on, in exactly the same manner as e-mail. Voice messages can be played using specialized player interfaces with controls that allow you to replay specific portions of a message. Callers often leave their numbers only at the end of their messages after they have been warned that only a few seconds of recording time are left—which, in turn, makes them rush when leaving numbers. As a result, the recipient of a message has to listen to it several times in order to write down the number. This visual-mail application comes in two flavors: Web visual mail and PC visual mail. With the former, users access and manage their mailboxes at a Web site using standard browsers; with the latter, subscribers use a standard Internet mail agent to access their mailboxes.
Even without the full set of visual-mail capabilities, the following two simple unified messaging features explore the duality of the vocal versus visual access:
1. Bridging. Telephone numbers are converted into e-mail addresses and vice versa. Voice-mail users can send their messages to the Internet; e-mail users can send voice messages to the PSTN.
2. Cross notification. Voice-mail users are notified of their e-mail reception; e-mail users are notified of PSTN calls.
Support of multiple languages is typical for advanced implementations of messaging, but one important language supported by the voice-mail part of the application is designed specifically for the deaf. The telecommunications device for the deaf (TDD) converts tones to alphanumeric characters and vice versa. TDDs have been used for communications with the deaf over PSTN lines, but now they can be naturally integrated with messaging.
As an introductory example of a crude mechanism of establishing something that approximates a telephone conversation (and is available to all owners of multimedia PCs connected to the Internet), consider the following exchange. A person speaks a phrase or two into the PC microphone and saves this message as a file (preferably in a compressed format). That file is then sent via e-mail to another person, who receives it (typically, in a matter of seconds), plays it, and produces a response in exactly the same manner. The conversation can go on like this indefinitely, and, if the files are not too large, this poor man’s IP telephony can be surprisingly efficient. This simple example vividly illustrates the potential of unified messaging.
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