System Management (Centrex or PBX)

IP-Centrex and IP-PBXs share features that make system administration easier, as compared with legacy telephone systems. The common trend is to push down more responsibility for system administration from the expensive expert to the user (which, in turn, is part of the larger push for cost saving that has all of us dialing complex number codes and counting out our own bank notes at an automatic teller machine). With IP telephony services and systems, the user may move an IP phone from one outlet to another on the same network, since the device is self-registering with the controller—so users could essentially handle the physical moves. Individual users can also set up some features on their own phones, such as ring patterns and tones, together with icons used on the screen.

An internal system administrator using a Web-based browser package can change calling features and forwarding patterns, set up UM mailboxes, and manipulate access to long-distance or international codes. This in-house capability not only saves the cost of work orders that were, previously, sent to the telco (which may charge $100 per hour), but also enables changes to be completed within hours, rather weeks.

With a major Centrex-based application (such as ACD for a contact center), managers, supervisors, and system administration personnel can view and print exactly the information that they need. This would include agent and group performance, load and profile management, and historical reporting.

An example of a system administration screen from Nortel's IP-Centrex Management package is shown in Figure 1.


Figure 1: System administration screen.

A prime characteristic of IP-Centrex is that the service is delivered over the existing LAN within a building or campus, and that a network management system for that is all ready in place. There will be the need, however, to enhance the management capabilities to support multimedia services over the previously data-only network. This VoIP traffic needs a high-performance, reliable, and flexible IP-network based on a set of techniques that will ensure the required QoS. The following list of action items is taken from a position paper published by Nortel Networks:

- Use a high-level, software-based policy manager to define and control traffic flow, especially for premium traffic.

- Control bandwidth utilization based on time of day, application priority, and network conditions.

- Separate traffic into queues.

- Mark and police entry traffic.

- Monitor traffic levels at each outgoing interface.

- Actively manage output queues.

- Filter exit traffic for security and congestion control.

- Use packet discard algorithms.