Several carriers are starting to integrate billing for campus-area and wide-area cellular services. Using Motorola's InReach radio system, for example, carriers such as Bell Atlantic and NYNEX (recently merged into a new company called, The New Bell Atlantic) have the ability to map the four- or five-digit PBX or Centrex extension to users' cellular phones. Cellular calls made on the company's premises are billed at whatever discount rates the company may have negotiated with the local telephone carrier for wireline services. When cellular calls are made off-campus, billing shifts to the prevailing cellular rate. This arrangement allows users to have a single phone number that follows them around throughout the workday. It also gives them the ability to call or be called by others in the office using just assigned extension numbers, regardless of their location at any given moment. The company benefits by obtaining lower cellular rates for calls made on-campus.
It is also possible to use existing cellular telephones with a wireless PBX system. Lucent Technologies' Definity Cellular Business System, for example, enables in-building and out-of-building mobility with the same Advanced Mobile Phone System (AMPS) cellular handset. For in-building calling, the IS-94 standard dual-mode cellular handset registers itself with an in-building base station and takes its commands from the wireless PBX. For out-of-building calling, the handset registers with the nearest public cell site transceiver.
In another example of system-service integration, AT&T Wireless allows users of Nortel's Companion Microcellular System to use the same handset for wide-area communication via its Digital PCS Wireless Service. The blending of the Companion Microcellular system with AT&T Digital PCS provides digital mobility services for complete enterprise accessibility, from the manufacturing floor, to the office, or on the road anywhere in the North American cellular network.
Users of AT&T Digital PCS with the Companion Microcellular receive unlimited wireless service at their facility or campus for a flat, low monthly rate. On site, they also have access to popular PBX features such as calling line ID, message waiting indication, call transfer, and conference capabilities. Off site, they have access to caller ID, AT&T VoiceMail with message waiting indicator, AT&T PCS Messaging (alphanumeric and numeric), and authentication for transmission security and fraud protection. Digital PCS handsets have about three times the battery operating duration of existing cellular telephones.
Each Companion Microcellular system can support up to 1500 users and covers up to 10 million square feet of area. Multiple systems can be linked to serve locations with more users or larger areas and also can be linked into private wide-area networks connecting multiple locations, providing employees with total mobility.
Companion Microcellular systems connected in a network of Meridian 1 systems can automatically register authorized Digital PCS handsets. For example, calls to an extension in a Seattle office equipped with a Companion Microcellular system can be routed automatically to the person with that extension when he or she is in a Dallas facility connected to the private network. Additionally, the person can make outbound calls and use the features of the networked PBX system in Dallas from the Digital PCS handset. While on the road between these two offices, the person continues to receive AT&T Digital PCS features.
There is always the chance that in-building calls will be captured by an outside tower, but in most such cases, the PBX dialing scheme will not work, alerting the caller that the signal was captured by the public network. This and other problems can be prevented by using radio frequency design tools to properly engineer the corporate network.
One such tool, available from Lucent Technologies, is a computer-aided design program called the WiSE (Wireless Systems Engineering) Expert Design System. It creates a model of the customer's premises to pinpoint ideal locations for wireless transmitters by considering all the necessary variables like building dimensions, construction materials, environmental factors, numbers of users, and "traffic" projections, when designing a wireless system.
The service integration concept has been carried a step further by AT&T Wireless. In select markets, the carrier offers its cellular customers the option of adding a personal base station for the home. For a flat monthly fee of $10 (plus the cost of the base station), customers can use the same cellular phone at home, on the road, and at the office. When users take their phones on the road, calls are billed at regular cellular rates. When they arrive at work, intelligence built into the network launches a cellular connection to their wireless PBX. At that point, calls are billed at the corporate rate for conventional wireline service.
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