Wireless PBXs

Wireless phones have become a common sight in recent years, with cordless handsets in use in the home and cell phones mounted in vehicles and carried around in purses and briefcases. Lower-cost handsets are more portable, offer better connections and wider coverage, and longer battery life. All this, plus improved service quality, have led to millions of people taking advantage of mobile communications. The success of mobile communications has led to a revolution in office communications.

With office workers spending increasing amounts of time away from their desks—supervising various projects, working at temporary assignments, attending meetings, and just walking corridors—there is a growing need for wireless technology to help them stay in touch with colleagues, customers, and suppliers. According to various industry estimates, as much as 75 percent of all workers are mobile, spending significant amounts of time away from their desks. This lack of communication can adversely impact personal and organizational performance. The idea behind the wireless PBX is to facilitate communication within the office environment, enabling employees to be as productive while moving about as they would if they were sitting at their desk.

Almost any organization can benefit from improved communications offered by a wireless PBX system, especially those engaged in:

§  Manufacturing. Roving plant managers or factory foremen do not have to leave their inspection or supervisory tasks to take important calls.

§  Retail. Customers can contact in-store managers directly, eliminating noisy paging systems.

§  Hospitality. Hotel event staff can stay informed of guest needs and respond immediately.

§  Security. Guards can relay emergency information quickly and clearly, directly to the control room or police department without trying to reach a desktop phone.

§  Business. Visiting vendors or customers have immediate usage of preassigned phones without having to borrow employee desktop phones.

§  Government. In-demand office managers can be available at all times for instant decision making.

Wireless PBX technology differs from other forms of mobile communications. Unlike cellular phone service, for example, there is no charge for air time. While cellular is a high-powered system designed primarily for high-speed use in cars, wireless PBX is used indoors and the mobile phones get better reception and longer battery life—up to 6 hours of talk time or 60 hours of standby time on a single charge.

When fully integrated into an existing PBX or Centrex system, all of the special call handling features are preserved. With Ericsson's Freeset system, for example, the wireless capability can be added to virtually any key, hybrid, PBX, or Centrex system to provide an integrated facility running both wired and wireless extensions. Mobile users have access to the same functions and features of the host system to which they are ultimately connected via the adjunct switch, such as caller identification, extension dialing, speed dialing, conferencing, hold, transfer, programmable buttons, and voice messaging. Another feature, call screening, gives users the control to effectively screen all calls before deciding to answer, or to distinguish an important call from one that is not important. The handset's built-in display screen shows the caller's name or number on incoming calls.

Some vendors offer applications development toolkits to bring value-added features to their wireless PBX systems. Nortel, for example, offers an open interface for wireless communications and computer-telephony integration (CTI) via its Companion Applications Toolkit. Using Nortel's Companion Applications Toolkit, developers can write PC applications such as database queries and fax and e-mail interfaces that mobile workers can access via their Companion portable telephones. An application can be initiated from either the portable telephone or a desktop PC. More than 100 PC-based applications can interact with one or more portable phone sets and all applications can reside on a single PC.

Under ideal conditions, mobile users have the same digital voice quality as conventional PBX users. Even the charges for outgoing calls are integrated into the same billing process as desktop phones. Wireless PBX also provides seamless communication throughout the building, including hard-to-reach places like elevators, tunnels, or parking garages.

Wireless PBX operates in a variety of frequency bands, including the unlicensed 1910- to 1930-MHz Personal Communications Services (PCS) band. The term "unlicensed" refers to the spectrum that is used with equipment which can be bought and deployed without FCC approval because it is not part of the public radio spectrum. In other words, since wireless PBX operates over a dedicated frequency for communication within a very narrow geographical area, it has little chance of interfering with other wireless services in the surrounding area. Consequently, there is no need for frequency coordination or FCC licensing. The individual channels supported by the wireless PBX system are spaced far enough apart to prevent interference with each other. Privacy is enhanced through the use of digital speech encoding and continuous frequency hopping to make eavesdropping nearly impossible.

The capacity of wireless PBX systems is easily expanded—portable telephones and base stations are added as needed—up to the maximum capacity offered by the vendor's particular system. Likewise, the coverage of wireless PBX systems can be expanded through the strategic placement of base stations and distribution hubs. While single-zone coverage up to 500,000 square feet effectively covers most office buildings, the addition of base stations and distribution hubs can achieve multizone coverage of up to 12 million square feet for a campus environment.

Substantial savings can accrue over time through the elimination of traditional phone moves, adds, changes. There is also significant savings in cabling, since there is less need to rewire offices and other locations for desktop telephones. This is significant because companies typically spend between 10 and 20 percent of the original cost of their PBX annually on reconfiguring the system.