About XDS

XDS Series of Boards
The XDS series of boards was designed to bring the switching capabilities of much larger switches to the PC platform. XDS, which stands for eXternally Defined Switching, is the third generation of switching products from AMTELCO. The first generation was a voice grade line concentrator introduced in 1977. The second generation, the AMTELCO Switching Peripheral, or ASP, was introduced in 1985. The ASP is a general purpose, flexible switch designed to be controlled by a host computer. It has been deployed in a wide variety of configurations with numerous PBXs, paging terminals, and voice storage equipment. The XDS series of boards, the third generation, draws on this experience to bring the same level of switching capability to PCs. XDS boards have found wide usage with Computer Telephony developers.

XDS Design and Concept
From the beginning, AMTELCO has focused on the interface to the public telephone network, the ultimate connection of any telephony system. Drawing on years of experience in dealing with a wide variety of equipment and telephone networks, the XDS boards are designed to allow the user to take fullest advantage of the various interfaces, while insulating them from the details of network operation with field proven firmware. These interfaces are designed to be robust in nature with ample protection and full FCC certification, where applicable.

The XDS boards are committed to the concept of open architecture. Interfaces exist to connect the XDS boards to various interconnect buses, both public and proprietary. This allows the boards to work with boards from other companies. These include MVIP™ (Multi-Vendor Integration Protocol) from developers like Rhetorex®, Natural Micro-Systems®, and Acculab®. Other companies include Dialogic® with SCSA® (Signal Computing System Architecture) and PEB™ (PCM Expansion Bus) bus structures. As new bus structures emerge, AMTELCO will be among the first to provide support for them. All XDS boards are intelligent, each having its own processor which is responsible for all the details of signaling detection and timing. This allows for a truly distributed architecture while placing a nominal burden on the host PC. A DSP is also included on each network interface board. This DSP provides a complete set of tone plant functions including DTMF detection and generation, call progress tone generation, and conferencing capabilities. For many systems, this will eliminate the need for a voice processing board, as the XDS boards can handle basic dialing and tone requirements internally. As each board has its own facilities, the scaling of systems is almost automatic.

XDS boards also address some of the inherent limitations of the PC architecture. Practically all analog telephone interface boards require a negative power supply of either -5V or -12V. PCs can typically provide only 0.5 Amp or less of either of these voltages. In order to avoid exceeding this limit when multiple boards are used, a local power supply located on each board provides the required negative voltage.