We figured out how to communicate on a Iridium Satellite phone using a aviation headset. I experimented and had success with an older 9505A and a newer 9575 Iridium phone. I use a Gulf Coast Avionics GCA-86A cell phone booster as the interface. I found that the clarity and volume of the conversation was the best when I unplugged the GCA-86A from the headset jacks of the aircraft thus eliminating the volume control of the aircraft intercom.
The Iridium phone has a 2.5 mm stereo jack. The GCA-86A has a 3.5 mm stereo jack. You need a 3.5 mm stereo cord and a 2.5 mm-3.5 mm adaptor. I purchased the cord and adaptor at Frigid North on Spenard road in Anchorage.
You need the following items to interface a Iridium phone to a aviation headset:
1. https://www.gulfcoastavionics.com/products/624-gca-86a.aspx
2. http://www.amazon.com/Parts-Express-3-5mm-Stereo-Cable/dp/B0002ZPJZO/ref=sr_1_1?s=electronics&ie=UTF8&qid=1395202269&sr=1-1&keywords=3.5+mm+stereo+cable
Note: Must be a 3.5 MM stereo cable. A stereo cable has three connection rings on both male ends. There are cable with four rings and cable with three rings on one end and four rings on the other end.
3. http://www.amazon.com/3-5mm-Stereo-Jack-2-5mm-Adapter/dp/B0002ZPFAS
Note: Must be a 3.5 mm to 2.5 mm stereo adapter. A stereo adapter has three connection rings. There are adapters with for connection rings.
