I went to radio shack last night and bought an 2.5 to 3.5 stereo adapter so I could use my 8820 in my car(I have an input jack to my car's system). Whether in headset mode or speakerphone mode nothing comes through car speakers except for some clicking. I took the adapter back and the Radio Shack dude said, "Oh, you need a different one. Here, try this one." Same thing happens. Does anyone have a specific brand and model that they know works for this application?