What is really exciting about VoIP is what you can do with it.
In other words, it's all about the applications.
But what, specifically, does that mean? How will your end users' lives be different- and better-once you've migrated to a VoIP infrastructure?
What new things will they be able to do? What old things will they be able to do better?
Many of the applications aren't conceptually new. Applications like unified messaging and collaboration (including video) have all been around for years. But they weren't widespread because they were expensive to build, deploy and integrate.
The use of IP and other industry standards makes these applications much more practical for deployment to a broad enterprise user base.
In addition, many other applications are new-or at least represent new ways of doing and combining existing applications.


Let's look at the following applications:

- Unified messaging, ( voice mail, email and fax )

- Conferencing

- Collaboration

- Multimedia


Unified Messaging

For years, PBXs have been able to integrate voice mail and email, letting users access voice mails in the form of email attachments that can be played out over the PC-or, conversely, users can have emails read to them through the voice mail system via text-to-speech (TTS) capabilities. But TDM-based unified messaging couldn't really be cost-justified on a standalone basis, and it never really caught on.

In the converged world, however, it's a different story. The narrow capabilities that went under the heading of "unified messaging" in the old days are simply features of today's larger collaboration packages, an addition to find-me/follow-me or presence capabilities.

The IP-PBX application packages offer the basic UM function of providing access to voice mail via a text interface, and vice versa. These packages either pull voice mail into a client, or can be integrated into Microsoft Outlook or Lotus Notes.

Where's the benefit in unified messaging?It allows users to be more efficient, listening to email while in their cars or otherwise away from a computer. Likewise, users can scan, prioritize, forward and otherwise deal with voice mails via a PC interface that may be handier and quicker for these purposes.
No more listening to multiple unimportant voice mails just to reach the one you are interested in.


Conferencing And Collaboration

Collaboration is advancing in the converged IP-telephony world through features such as document sharing, whiteboarding, Web co-browsing, and of course traditional audio conferences.
All of these features are included in the IP-telephony applications At the most basic level, audio conferencing as an IP-PBX application promises to avoid high per-minute service provider charges, as an enterprise can put all of its internal audio conferencing onto its IP WAN.

But the real promise is that these collaboration applications can change how employees work, allowing them to work together remotely and spontaneously.
The ultimate goal is to be able combine all the capabilities in an ad hoc session, creating a dynamic collaboration environment.


Here's the scenario as typically envisioned:

One colleague dials a second by detecting their on-hook status in the "buddy" or presence list of the convergence-center PC client, and right-clicks to connect on a basic phone call.
They decide to add a third participant who is also available, and are able to conference her in on the fly by dragging her name over the "conference" button. The three decide they need to review a particular document, and they are able to call it up from wherever it's located and edit it together, each passing and seizing mouse and keyboard control in turn.
If all are equipped with desktop video cameras, they can decide to enable video as well.
The document is updated, the colleagues agree to the actions required upon completion of the conference and the call concludes with a click.


Multimedia

Speaking of video, or multimedia, there are huge opportunities for growth in this market as enterprise networks converge.
"Video is coming to a desktop near you." Another reason why video is coming soon is cost.
And even more cost is being driven out of the networks that carry enterprise video traffic. Earlier generations of videoconferencing required expensive, less reliable ISDN connections among sites, while the new systems are built on IP. That can mean impressive savings.
The exact cost won't be as easy to determine, however, because the IP LAN/WAN must have sufficient bandwidth and, more important, quality of service (QOS) to carry the video traffic.


Presence

One type of application that's somewhat new is "presence." The name comes from this application's ability to let colleagues know where you are or, more accurately, where you're reachable.
Presence packages are built on the model developed for instant messaging (IM) "buddy lists." With basic consumer IM services from AOL, Microsoft or Yahoo, the user adds members to his/her buddy list, and each time the user goes on line, he or she sees which "buddies" are also on line and available for text chat.
An advanced presence "portal" lets users see not just whether a colleague is logged into IM, but their reachability status via various media.

Whether their telephone is off hook, whether they're logged into the messaging system for IM or email.
Obviously an application like presence was, if not impossible, certainly impractical in a traditional environment where voice, email and instant messaging all resided on discrete systems that would have had to be integrated via APIs and expensive middleware.
With IP-telephony, all these capabilities work as part of the same system.
As a complement to presence, an enterprise can also deploy "find me/follow me" call routing. As its name suggests, this feature lets a user provide call routing instructions based on factors like time of day or calling party, to determine where individual calls should be delivered-office phone, cell phone, direct to voice mail, etc.


Productivity Benefits

Though most executives shy away from including applications-related productivity benefits in the formal business case productivity gains appear to be available from using IP-telephony.


The Call Center

Computer-telephony integration (CTI) applications form the basis for today's call center, providing "screen pops" and other features that customer service reps (CSRs) now depend on to provide strong customer service.
But CTI never caught on outside the call center, nor was it affordable for most smaller call centers.
That's now changing. Many smaller companies that couldn't afford CTI applications or integration with TDM PBXs are purchasing and deploying IP-based contact center packages. And for larger operations, the potential benefits are even greater.

Just as IP allows the basic voice infrastructure to be more centralized where appropriate, the customer contact applications-CTI routing, voice response, workforce management, reporting analytics-can likewise be concentrated at the enterprise datacenter.

Off this centralized implementation, the enterprise can serve a much more widelydispersed agent population, creating a true "virtual call center" in which customers can be routed to the optimal agent for their needs and for the company's cost metrics. These agents can be working at any location-including their own home, saving on office space and other call center operations costs.

Finally, convergence allows the "multimedia call center" to become a reality. Customers can contact the enterprise via phone, email, the Web, even video kiosks, and have their contact routed to the agent with the appropriate skill set.
These media can all be provisioned as part of the same converged platform.


Will applications drive infrastructure convergence, or will infrastructure convergence drive applications?

Probably a little of both.
As customers find themselves migrating to convergence as a natural part of the infrastructure replacement cycle, they'll start to see glimpses of what the new applications can do for them, and this will help inform and possibly even accelerate the migration. .