We have iridium in our S76. It works very well, and we use it to pass operational information back and forth. We can also take it out of the aircraft for a hand-held, but usually our mobiles are preferable.
It costs around $3 US to connect a call, and most of our calls are only 20-30 seconds. It was a total PITA to fit the kit. The manufacturer's instructions were garbage, the installation kit was missing some parts and we had to manufacture another part ourselves.
The wiring diagram was totally wrong and could never work. But our engineers designed a method, and got it to work. Running the wires through the roof to the antenna was another story!
