IP-Centrex—Prospects and Pilot Trials

IP-Centrex—Prospects and Pilot Trials
Because relatively few organizations have implemented IP-Centrex on a commercial basis and many telecom service providers work in a highly competitive environment, it has been a challenge to obtain information about appropriate case studies. The situation of a large Centrex customer, which participated in a limited IP-Centrex technology trial, is then described in some detail. Finally, we include descriptions of several IP-Centrex trials for which some information has been made available.

IP-Centrex Prospects
A municipal government that serves a city of over 250,000 people has 900 full-time employees supported by Centrex in 70 locations, some of which are indicated in the map in Figure 1. The city's Works Department has a fairly modern 120-station PBX, rather than using Centrex, because it is located outside the serving area of the main Centrex-providing CO. The municipality's Centrex service contract is approaching the end of its 10-year term, during which it has provided each line at an attractive 50% discount off the current rate. A new Centrex contract would look expensive to the city because of structural changes in the tariff within recent years. The CIO of this city, therefore, faces a dilemma regarding the annual telephone service bill of $300,000, with the choice of moving to a network of conventional PBX systems, investing in anew IP-PBX infrastructure, or hoping to use IP-Centrex as being suited to an organization with many small offices. There is a serious drawback with each alternative as the system vendors wind down the development of circuit-switched PBXs; the technology of IP-PBXs seems not yet to be settled and the local ILEC cannot offer a schedule for IP-Centrex availability.


Figure 1: Municipal locations.

The city owns an optical fiber network that can be linked into locations housing 90% of its personnel. This fiber is installed in ducts that were primarily used for the copper cables linking traffic lights to the traffic control computer center.

Probably the best solution is to negotiate a 1-year extension to the present Centrex contract and hope that the options become more clearly defined meanwhile.

A newly organized health care corporation needs to integrate the services of four hospitals, located as on the map in Figure 2. The hospitals and associated clinics employ about 1,500 phones and 50 fax machines. One-third of the phones are single-line, analog sets and are in patients' rooms. The largest hospital in this group, with about 50% of the lines, has a seriously out-of-date PBX and overloaded voice mail/autoattendant subsystem. A major objective is to present a single image to the public served by the health care corporation, as each site will concentrate on selected specializations to achieve optimum economies of scale.


Figure 2: Healthcare network integrates four hospitals.

The corporation's board also intends to implement video communications extensively, within a short time frame, to minimize travel time and expenses, for both professional staff and patients. IP-compatible video-conferencing units from several well-established vendors are now available at very competitive prices.

Because this health care organization is in a small, rural town, beyond commuting distance from a large city, it has great difficulty in recruiting and retaining well-trained telecom professionals. Additionally, this market area is not yet attractive to competitive broadband network providers. A deployment strategy that uses IP-Centrex at the largest hospital and integrates three existing small-to-medium PBXs into the corporate network with IP trunk gateway cards is probably the best solution. TI links leased from the telco will serve sites W and E, while the smaller hospital at N will have frame-relay data service at a fractional TI bit rate.

A solo consultant has been a small Centrex customer for 10 years, working from his home office. The positive side of small Centrex is that lots of features (including calling line ID and three-party conference calling) are bundled into the service with no extra costs, at a rental not much above that for a basic business line. The negatives are that there have been no service improvements for a decade, the service is not well marketed, and no one at the local telco's office is willing to talk about small Centrex. The service provider has, obviously, not tried to mine its customer database or to get new services out to these small businesses. Additionally, this customer has not received one sales pitch from any Centrex reseller, in the last 10 years, to sell competitive services. Another concern is that the electronic business set (EBS), which has digital signaling, uses local ac power and is not on during a power failure.

To provide for good service quality, this small office requires two Centrex lines and needs three "PSTN accesses" so that two calls can be handled simultaneously and a third call can be diverted to voice mail. One of the two physical Centrex lines is defined as analog, to serve a fax machine, and that line is also used for ADSL, providing high-speed Internet access. The total monthly rental for two Centrex lines and three network accesses (not including the ADSL service) is about $80.

Since there are no restrictions on access to competitive services, the consultant rents unified messaging from Sprint (at approximately $10 monthly for 200 minutes of storage), because a single voice mailbox is provided for calls to the Centrex wireline phones and to a cell phone. The ILEC, which provides the small Centrex, has configured its own voice mail service in a way that does not allow call forwarding from any number other than the Centrex line. This customer has installed a total of six outlets in his house, so that he can move phones, fax, or modem around without paying any relocation fees.

For small and home office (SOHO) users, the prospects with IP-Centrex are as follows:

- All services will use one DSL access line.

- Some Computer Telephony Integration (CTI) functionality, such as the availability of an on-line dialing list, will be available.

- Programmable IP telephones that receive DC power over the wires from the CO will be sold at reasonable prices.

- Integrated UM service will be accessible from a cell phone, or other mobile devices, in most locations, if served by a digital radio network