The four-line D/4PCI board is useful for small- and medium-sized enterprise computer telephony (CT) applications that require high-performance, cost aggressive voice processing but don't need the large-scale system sophistication of SC bus or CT bus-based products. The D/4PCI board uses the same application-programming interface (API) as its predecessors, making it easy to scale existing applications to take advantage of its power and features. The D/4PCI board has improved voice quality and automatic gain control (AGC) so that even the weakest telephone signals can be recorded and replayed with clarity. The D/4PCI board uses digital signal processor (DSP) voice processing technology, making it ideal for server-based CT systems - particularly under the Windows operating systems. The D/4PCI board is optimal for client or small server system development. The board offers DSP power and memory capacity that provide a base level of performance for requirements as well as the "head room" for future application expansion via software-based technologies.