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PBX Enhancements and Trends

The PBX increasingly is being positioned as a communications server for voice, data, video and image communications [4-3]. Some manufacturers are building such capabilities into the PBX itself. In October 1995, Lucent Technologies announced its Multimedia Communications eXchange (MMCX) server to support all customary PBX telephone features on multimedia calls. Such calls can involve voice, data, and video from any form of private or public network. The typical approach, however, involves high-speed interfaces to a variety of applications processors. This approach allows specialized processors, often developed by strategic partners, to perform their various functions to maximum advantage on the most effective platform, while also providing application integration through the PBX. The following PBX developments and trends exclude computer telephony integration, which will be discussed at the end of this chapter.

Reduced Instruction-Set Computing (RISC)

RISC processors provide for faster call processing through the use of a reduced set of operations commands, as compared to traditional CISC-based (Complex Instruction-Set Computing) processors. Although the set of executable commands is reduced, the increased speed of processing is thought by many manufacturers to enhance system performance. RISC-based processors increasingly are being incorporated into PBX system design, with Lucent Technology’s, Definity G3r, and GPT’s iSDX systems being notable in that regard [4-8].

PBX-to-Host-/LAN

This link lets users access computer applications through the PBX, sharing the same cable and wire plant as do the telephone terminals. Connectivity between the PBX and a host computer or LAN can be accomplished via such means as ISDN links or 10 Mbps Ethernet links [4-9].

Data Communications

PBX manufacturers have long supported modem pooling and low-speed data through terminal interfaces for data communications. Several manufacturers now support X.25 packet-switching interfaces. Although at considerable cost, Intecom and other manufacturers also support high speed connectivity, including Ethernet and FDDI. Additionally, a number of PBX manufacturers are developing interfaces for ATM (Asynchronous Transfer Mode), which clearly is the network technology of the future. No such interfaces have yet been offered commercially.

Wireless

Wireless communications are currently available for selected users through a special PBX wireless applications. Special PBX ports support wired connections to antennae distributed throughout a large office complex or campus. Selected users who require mobility can take advantage of special cordless telephones to communicate as they roam through the organization as long as they remain within the limited range of the antennae. Manufacturers of such applications include Ericsson and Motorola.

Fax Messaging

Fax messaging is supported by manufacturers such as Nortel (nee Northern Telecom) and Lucent Technologies. Through the voice processing system, prompts allow the transmission of a fax message, which is stored in a user-specific fax mailbox. The user can the access that fax message onscreen at a workstation, much as he would access a voice message from a telephone terminal.

Videoconferencing

PBX videoconferencing is offered by such manufacturers as Fujitsu, AT&T, Nortel, and Siemens Rolm [4-7] and [4-8]. At relatively low speeds over the PSTN, the circuit switched connections are often less costly than are dedicated videoconferencing links. Although generally based on international standards, the terminal equipment typically is proprietary, with the trend being towards more substantial standardization.

Asynchronous Transfer Mode (ATM)

ATM, which will be discussed in detail in Chapter 11, is being examined by PBX manufacturers for broadband communications within the confines of the system, itself. Additionally, ATM compatibility will be provided to the Wide Area Network (WAN). While ATM and PBX switching has been demonstrated in a mode of coexistence, ATM switching has yet to be incorporated into the PBX itself. As the future of ATM in the WAN is virtually assured, as ATM finds its way into the LAN world, and as manufacturers of LAN switches and hubs increase their capability to support voice and video, the PBX manufacturers increasingly will feel the pressure. At the very least, they likely will incorporate ATM switching matrices alongside the standard STM (Synchronous Transfer Mode) matrices currently used to handle voice. The yield likely will be a PBX/ATM router combination [4-10].

PC-Based PBXs

PC-Based PBXs are also known as dumb or programmable switches, have been around for a long time, but generally have not been well accepted. They typically consist of a dedicated 386 or 486 PC, program logic, a switching matrix card and a port expansion unit that provides 16 or more ports. Some systems (VCO Series/80 Open Programmable Switch) involve a switching matrix which is expandable to 4,000 ports. Traditionally, PCs have not been considered reliable enough for such a mission-critical application. Neither have general purpose computers been proved to be stunningly capable of switching calls or providing significant feature content. Those limitations appear to be lifting. Indeed, some strongly suggest that the PC, PC LAN, or Client/Server computer will be the PBX of the future. The low cost of such systems (approximately $200 per port) is a point in their favor, at least in the very small PBX market. Manufacturers include Amtelco, Dianatel, Excel, New Voice, Redcom, and Summa Four [4-11].

Security

Security is of increasing concern, as hackers have penetrated PBXs, Voice Processors (very easy) and other systems to gain unauthorized access to networks and various information resources such as critical databases. PBX, computer and peripheral manufacturers have enhanced security through enhanced software and hardware which can act on either a passive or active basis to deny or terminate such access or, at least, to recognize its occurrence and alert the system administrator of that fact [4-12]. While such products are widely available at reasonable cost, relatively few PBXs are properly protected. It is estimated that unauthorized network access via the PBX results in toll fraud of $2 to $4 billion in the United States alone [4-7].


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