Avaya only supports MOH with a Aux. Trunk card and a 909a/b universal interface. With that said and out of the way, you can use a analog port but you need to limit your output to 1watt.Use a headphone output to keep the power down. If you can get a 909 or a system-25 MOH adapter that will keep you under 1watt. I like to use a PC speaker plugged into a walkman headphone port and the PBX plugged into the PC speaker headphone jack. This gives you a way to test the music service and listen to something while working in the phone room.