In the first attempt to use a phone cradle for my Motorola 550 flip phone with an interface for the airplane radios. I ran into this. Phone in cradle and turned on. Plane at the run up area and I hear ATC comms in my David Clarks, Phone rings and I hear the phone conversation in only 1 of the earpieces. Works as designed. Then I decide to talk on the phone and I was actually transmitting to ground control.
Then I hear this. "Somebody is really pushing the wrong button, check your radios guys..."
realizing it was me I flipped the phone shut, unplugged it, Had my co-pilot talk to ground because I knew they would recognize my voice. We got clearence clarence and blasted off. When I went back to theradio shop where i bought this cradle the guy tells me it has a few bugs... I did get my money back and I never saw those cradles again..