Where everyone starts: The Traditional Phase

Enterprises operating in the Traditional Phase typically have separate physical networks for data, voice, and video (if used). Each location usually has its own LAN, and the enterprise as a whole has a private, dedicated WAN running IP protocols for computer data. If an enterprise has a small number of locations, it may vest its WAN infrastructure in a Virtual Private Network (VPN) that optimizes access costs by using the Internet as the WAN transport.

Telephone system needs are typically met through one or some combination of one or more of the Final Four models covered in Part II. Unlike the packet-switched network infrastructure of the computer data enterprise network, telephony system needs are ultimately met through the circuit-switched protocols of the PSTN. In-house PBX systems, which may be interconnected over dedicated lines using Time Division Multiplexing (TDM) protocols, is about as good as it can get.

Videoconferencing solutions depend on the size of the enterprise and the type of videoconferencing application needed, such as point-to-point, multipoint, or desktop. The videoconferencing needs of an enterprise can be met by using dedicated or switched transports that run physically apart from the data and voice networks. Or these needs can be met by using the voice infrastructure (in the TDM world, underlying video requirements tend to follow those of voice) with some modification. For example, terminating equipment to support video would be needed at each location to support the application. But a video module can be used in the PBX to bring up a video call and to dynamically allocate bandwidth for the life of the video call.

In the Traditional Phase, on an interim or permanent basis, VoIP Gateways may be used to support POTS-related calling from the LAN side into the PSTN. Companies operating in this phase typically use cheaper, switched multi-channel transports such as a Primary Rate Interface (PRI) line to the PSTN. Quality of service equals that of POTS.

Making progress: The Converged Networks Phase

In the Converged Networks Phase, most enterprises build out their computer data networks to support IP telephony on the LAN side at all locations and VoIP on the WAN side. As a result, one common infrastructure exists across the enterprise to support data, voice, and videoconferencing. This arrangement enhances the IP network to meet enterprise-class criteria, such as improving quality of service and increasing the reliability of real-time, mission-critical business and communication applications.

The organization benefits from a distributed communications architecture that minimizes the monthly recurring cost of transport access lines into both the dedicated and switched carrier services networks. Dynamic bandwidth allocation is optimized across all applications. In addition, the toll charges associated with the traditional regulated carrier services of the PSTN are minimized if not eliminated altogether.

In addition, the organization can begin to develop integrated data, voice, and video applications. Most if not all of the call features described in Part I become available across the enterprise. As the higher recurring costs of running separated networks are driven out of the budget, more operating revenues are made available for other business needs. As the organization deploys and leverages its IP infrastructure, it positions itself to integrate new applications as they become available.

Getting there: Converged Communications Phase

As enterprises become more distributed and business performance needs dictate enhanced user capabilities, converged communications applications are deployed. Converged communications leads to increased flexibility and cost efficiency due to modularization of components and applications. As solutions become more modular, their services can be deployed in a greater number of configurations and more easily integrated into multi-vendor environments.

Avaya is taking the lead in modularization of its software and systems into open communications architecture to help organizations smoothly transition to converged communications for a more adaptive enterprise.