Something like 3USD/min it looks like. At GSM's 13 kbit/s, that's ~0.4cent/kbit. It doesn't sound like a significant cost to report a position regularly at that

Something like 3USD/min it looks like. At GSM's 13 kbit/s, that's ~0.4cent/kbit. It doesn't sound like a significant cost to report a position regularly at that rate, not compared with the cost of flying an airliner anyway.