Once, a few years back, from LH aircraft. Called a reative who was in total panick (for a silly reason, but it took me a long time to calm her...) Was on my cell while taxiing, the FA was really nice about it but asked me to turn it off as we were first in line on the runway... then as soon as we reached cruising altitude I used that $$$ phone. I think it was like $30 for a 3-minute call... but the relief of my relative was worth it.