Just had a Skyconnect system fitted into our 902 HEMS machine via Avionics Mobile. The clarity is very good once you are connected, but that can sometimes take a couple of attempts. Price depends upon if you are calling a landline, mobile or another satphone. Cheapest is sat - sat.
We are also currently trialling a tracking package which interfaces with our mission management system, giving our despatcher location, heading and speed information with altitude pending. This info is sent via the satphone at 1 minute intervals whenever the phone is not being used for voice comms, and the aircraft is tracked on a moving map. Working very well so far.