New Switch-Ready CT Boards

Computer-telephony (CT) boards plug into extension slots of a standard PC or into the passive backplane of industrial-strength computers. They interface to the public network or the PBX, perform a variety of voice-processing functions, recognize DTMF digits, and then initiate an outgoing call or switch to additional resources (e.g., fax-on-demand service, voice recognition, or text-to-speech). To share resources within the PC chassis, these boards interconnect via a telephony bus -- either Multi-Vendor Integration Protocol (MVIP) or Signal Computing System Architecture (SCSA).

The digital-switching matrix that many CT and line-interface boards now carry is a chip set that you can program for the switching and conferencing of digitized voice signals. Mitel 's MT8980 chip, for example , switches pulse code modulation (PCM), digitized voice, and data under the control of a microprocessor.

The major vendor of SCSA-compatible CT boards is Dialogic (Brussels, Belgium). You can get MVIP boards from companies such as Rhetorex (Bracknell, U.K.), Pika Technologies (Kanata, Ontario, Canada), and Bitfield (Espoo, Finland), but there is no dominant board vendor in this camp. Market studies say that the SCSA front sells more boards, but you have more choices in the MVIP camp. Over 150 MVIP-compatible products are available from more than 50 companies worldwide. Functionality and pricing are similar, but you cannot mix and match boards in the same PC housing. However, an SCSA-compliant PC will operate with an MVIP-compliant box (via multichassis MVIP).

Most CT boards are for the ISA bus, but many vendors are making the move to H.100 and PCI, thereby capit alizing on PCI's bus-mastering and DMA capabilities. Expect to see these new PCI boards at the beginning of next year.