An adaptor unit for a voice operated typewriter employing morse code to provide a voice operated hands free telephone dialling facility. The unit consists of a four-bit counter interconnected with a multi-vibrator so that the counter is incremented by each pulse generated by the multi-vibrator and so that the multivibrator is held off when the count is zero. When a number is written into the counter from the voice operated typewriter employing morse code, the multi-vibrator is enabled to generate the requisite number of pulses needed to restore the count to zero.