The Centrex Alternative

Centrex is "basically normal single line telephone service with 'bells and whistles' added." While this is undoubtedly true for a large percentage of installations that want dial tone and perhaps a few extra services, Centrex is now offering more flexibility and features than in the past. Let us start with the basics. Why would an organization want to lease its entire infrastructure from the local telephone company rather than buy its own PBX? The most important reasons include:

  • Low start-up costs. The equipment and software is owned, stored, and kept up-to-date by the carrier. Fees are a direct multiple of the number of stations and therefore highly predictable from year to year.

  • Ease of physical movement. If employees move to new offices, the "virtual" telephone system easily moves with them. The risk of moves is diminished.

  • Cafeteria-style features. Features are available on an ad hoc basis; users pay only for those they use.

  • High uptime. Centrex service runs off central office-class PBXs (or soft-switches) and therefore is unlikely to fail. Of course, the risk from cable cuts or other external factors is unchanged.

There are some disadvantages:

  • Higher costs for volatile environments. Costs could easily escalate beyond an in-house PBX if users frequently move offices, require special services, or require special technology (e.g., computer telephony integration applications, such as screen pops).

  • Potential loss of service flexibility. If the culture of the organization is "do it now," there could potentially be a conflict with operating under the provider's set schedule for moves, additions, etc. This disadvantage is somewhat lessened if the service provider offers IP telephones that can be logically moved by software.

  • May not scale. While Centrex can certainly scale physically, it may not scale economically. As the number of users goes into the hundreds and thousands, the law of large numbers comes into play. Trunk lines can be reduced on a per-person basis, technologies and expertise can be spread over many more phones, and generally per-unit cost can be driven down.

  • Feature availability. While Centrex offerings usually have the standard telephony features such as call forwarding, speed dial, park, etc., certain special features may not be available. If the organization wants something specific that is not a product offered, bringing telephony in-house may be required.

No comments:

More?