Try using the the single prong headset in the two prong jack. I believe that this headset should work with both reception and transmission. I remember, Boeing on aircraft deliveries equipping some 737-800s that my previous company took from Seattle, coming with single prong headsets fitted into the two prong jack without adapter and they worked for reception and transmission. Sorry to say but the pilots that took delivery of the aircraft also assumed that they could take delivery of the headsets and did. So try it out. The single prong plugs into the larger jack outlet and if I am right about what I said then it should work for transmission as well.