Old analogue system like VHF, line-of-sight. Known of connection upto 200km away. Use of analogue in aircraft upset cost charging system because of ability to connect at such great distances.Digital system uses a switch that ignores any set that has a delay equivalent to about 25km range. Am still concerned that digital phone signal could be misinterpreted by onboard digital equipment as a legitimate command signal. Although have read documents on experiments trying to immitate or repeat interference without success.So as SLF always turn mine off. But have it on when I'm flying myself.
Mr Seimens would only be interested in this system to rip off SLF with exorbitant satellite phone charges. (Of course with a bit of a kickback to the airline.)
Regards
Mark
(Kap just beat me)