October 1998

BY MARTIN LIPPMAN

The fax board as we know it is dead. The traditional intelligent fax board requires fixed-function fax chips provided by fax-modem chip companies for each fax port. These boards do their job, but they're expensive and inflexible - each board in the system performs its own function. This functional separation made sense when DSPs used for voice processing were expensive and relatively slow, PCs were running DOS, and computer memory was expensive and hard to come by. However, today's DSPs are outpacing Moore's Law in their increase in computing speed - 300 MIPS PCs are running Windows NT and Unix, and computer memory is inexpensive and readily available. In today's computing environment, this traditional system architecture no longer makes sense.

A 1980s ARCHITECTURE
Until recently, the use of intelligent fax boards was limited by their high per-port prices and complex installation procedures. The intelligence of these fax boards comes from circa 1980s 8080-speed processors that offload T.30 processing and file conversions from the host PC. These on-board processors were extremely valuable when the host platform was a DOS-based system using Intel 286 CPUs, and memory was limited to 640 KB.

The fax modems on the intelligent fax boards were supplied by special-purpose DSP fax chip sets. One chip set was required per fax port, making the per-line component cost of the board quite high when compared with a voice board. The amount of board real estate these chips required and the power they consumed also limited the number of ports that the fax board could support.

AGE OF INTEGRATED MEDIA
With today's high-speed Pentiums offering hundreds of megabytes of RAM, the intelligent fax board's on-board processor is no longer needed to off-load the host PC - it can be freed to do other work instead. DSPs are becoming so powerful that it makes less and less sense to limit a media-processing resource board to only one medium. Fixed-function fax boards are giving way to powerful, integrated-media multiline boards that combine software (including fax modems and T.30) with programmable DSPs that can support multiple media. The advantages of increased density and the ability to easily upgrade DSP fax modem software make the programmable DSP-based board the preferred choice of system developers - even for systems that require only fax functionality.

When a system is built from these value-adding components, the board in the system configuration need no longer be relegated just to fax. The type of media (voice, fax, data, speech recognition, video) the board is processing is determined by what media-processing software is resident on the DSP. The board could be configured to process only one of these media, voice for example, or the board could be processing all of the media on whichever port requires it. An OEM or application developer creating an integrated-media system from these software-defined components will find development is faster than assembling fixed-function boards and integrating their functions via a PCM (Pulse Code Modulation) highway, such as SCSA, MVIP, or H.100.

WHERE INTEGRATED-MEDIA BOARDS SAVE
Using Fixed-Function Boards
The efficiency that integrated-media boards can bring to a system such as fax on demand is readily apparent. A typical one-call fax on demand (FOD) system answers an incoming call from the handset on the caller's fax machine. It plays a series of messages, and collects DTMF or spoken responses that assist the caller in selecting documents. The system than transmits the requested fax to the caller's fax machine, which receives the incoming fax in manual mode.

With fixed-function boards, building this system requires answering the call, playing outgoing messages, and collecting incoming DTMF on the voice board. The system could switch between the voice board and a speech recognition board to play the voice messages and collect the incoming spoken answers - it would then switch back to the voice board to play the message that prompts "wait for the tone to press start on the fax machine." The system then spends time locating (previously reserving) an available fax port on the fax board, switching the call to the fax port while maintaining the connection to the incoming line, and sending the fax.

The number of voice, fax, and speech recognition ports available to the system is determined by the number of ports of each media on the fixed-function boards in the system. There will always be a fixed number of voice ports, fax ports, and speech recognition ports on the system - adding more ports of any medium requires opening the system and adding boards (assuming there are any remaining empty slots). And, to complicate the development process even further, each of the media-board vendors provide proprietary APIs to control the functions on their boards. Any integration of these boards beyond the inter-board PCM connector is the responsibility of the OEM.

Using A Multimedia DSP-resource Board
With a software-defined multimedia DSP-resource board, the system is much different. The developer answers the call by issuing an "accept-call" command, followed by a "play-message" command with the port configured for voice. It then captures the incoming information via DTMF or speech recognition software using the DSPs serving the same port, executes a command that plays the voice message to prompt the caller to wait for the fax tone, and sends the fax by issuing a "fax-send command."

The board-level software can come from a variety of sources. In the traditional single vendor solution, the board vendor must provide the media as an optional software add-on; with open architectures it can come from a third party.

INTEROPERABILITY ISSUES
Several CTI board vendors have announced programmable DSP-based products that support multimedia, including voice and fax. Whether vendors do these implementations independently or in conjunction with a third party, the effort is still significant because they are based on widely differing proprietary board-level architectures. Even if the boards use the same DSPs, the implementation will require significant engineering resources from both companies because each board vendors' architecture remains proprietary and different.

Organizations such as the MSP Consortium are promoting industry standards for board-level architectures to expand the addressable market of CTI board and DSP-software vendors' products. If these efforts are successful and common board-level architectures and media APIs are generally adopted, the effort involved in providing third-party media on DSP boards will be greatly reduced. Media suppliers will be able to anonymously offer their fax, data, speech recognition, or video software on whichever boards are built to the architectural standards. OEMs will have a choice of best-of-breed media processing software, and no one will mourn the passing of the traditional fixed-function fax board.

Martin Lippman is the vice president of marketing for Commetrex Corp. Commetrex develops, produces, and markets software products for computer-telephony integration original equipment manufacturers (OEMs), system developers, and integrators. These products are business-enabling system-resource tools used to develop and produce communications systems supporting multi-line fax, data, video, and voice. For more information, contact the company at 770-449-7775, or visit their Web site at www.commetrex.com.