The EV6240 Evaluation Kit comprises a single board containing two CMX624 or CMX644A devices, line interface components, PIC C with serial communications port for PC interfacing. A reduced AT command set is used to communicate with the evaluation board via standard terminal emulators. The board is powered from a single 8-24V dc power supply; an on board regulator and two discrete components set VDD to provide 3.3Volt or 5Volt operation. LED's indicate device interrupts, carrier detect and hook relay status. The CMX6x4 devices may be driven from an external clock, or from their own crystal oscillator. Important signals can be monitored via test points. The CMX6x4 devices are socketed for easy replacement. A user prototyping area is provided. On-board miniature switches allow the user to select the required line interface and appropriate evaluation device crystal. The CMX6x4 supply currents may be measured by removing jumpers. Where components are telco-specific (line impedance, line protection, etc.) space is provided for the user to add appropriate components. The EV6240 PCB is suitable for CMX624 and CMX644A evaluation.