The telex 850 gets its power via the headset jack. It will work on any aircraft even a Cessna. Because that source is very low power it’s ANR is weak. The standard airbus jack has 5 pins. One pin is a dedicated power source that allows full ANR. That assumes however that your aircraft have power to the fifth pin. It’s a Airbus option. On the 330 for sure and sounds like the A320 series the pin is unpowered. Delta did not pay the extra 100 bucks for that option.