In the last few days OnAir have pulled out of their agreement with Ryanair. The airline is now looking for a new partner for the fleet-wide launch.
News : Ryanair to move to new in-flight communications partner
I have to say, on the few occasions I was flying on a compatible aircraft I enjoyed this service while it lasted. At least it was useful for free incoming text-alerts at 40,000 feet! However, perhaps that is precisely the problem. I never saw anybody actually make or take a call!