The EV6120 Evaluation Kit comprises a single board containing a CMX612, line interface components, PIC Controller and the option of using either the on-board 4-line LCD module or interfacing to a PC via a serial communications port. For the latter mode of operation Windows software is supplied. When using the LCD module two push-button switches are used to select the EV6120 functions. The board is powered from a single 8 - 24V dc power supply; an on-board regulator sets VDD. LEDs indicate control, and detect line status (IP, MODE1, MODE2, DET and MUTE) and the CMX612 may be driven from an external clock, or from its own crystal oscillator. Important signals can be monitored from test points. The CMX612 is socketed for easy replacement and a user prototyping area is provided. On-board circuitry may be used to implement a wetting pulse and to place an ac or dc load on the line. An opto-mos relay connects the 2- to 4-wire interface/op-amp hybrid for voice communications to the line. An external phone socket for adjunct box demonstration is provided, the connection to which can be disabled with a relay. A mutable local voice input and DTMF generation (for CIDCW acknowledgement tone) are provided. Where components are telco-specific (line impedance, line protection, on-hook loads etc.) space is provided for the user to add appropriate components.