BC118 - AIO2 Logic/Voltage Levels

On a BC118, Does anyone know what the AIO2 guaranteed voltage levels are for the AIO2 output when using the MelodySmart software? Looking for what the minimum voltage is for a logical high and what the maximum voltage is for a logical low. I have this AIO2 output tied to an A/D converter input on my MCU to detect the AIO2 logic since my MCU is powered by 3.3V and the AIO2 is powered by 1.35V.