Peter wrote:
The main drawback is that you need to maintain a contract SIM card in them
Yes, it is something like 5-12 EUR/month with about 6GB of data I think. I am pretty sure – including roaming.
That is still way cheaper than a satphone. The only question is – if that would work at all 
I am thinking now about the antenna. Should it be rather a panel antenna or a whip? A whip would be much easier to install in a drain hole in aft lower fuselage.
Edit: Maybe a “tube” antenna would be the best of two worlds…
Raven wrote:
I am thinking now about the antenna
https://www.sensorantennas.com/product/quad-gsm-antenna/
Raven wrote:
if that would work at all
In my experience such industrial style devices will not outperform the latest iPhone. The development cycles are much longer etc. Chances are high that getting simply the latest iPhone from the store will have better performance than a few years old low volume device with some customer supplied antenna. Also it saves you from getting another SIM card. If the performance of the phone is not enough better spend the money on a satellite solution. So many people have tried this over the years and the result was always the same. It works a little but can not be made work good enough to be reliable.
Lately I did even file a new flight plan in flight to EDDE at 5000ft to the east of the airport. But to the west of the same airport on the IFR departure there was no signal at all, nothing. That is what it will most likely be no matter which antenna etc…
Thanks for the link.
You may be right.
I still however hope that my iphone is:
- not powerful enough to transmit the signal from above the ground station where all antennas have horizontal characteristic.
- is additionally shielded by the metal cage while inside the aircraft.
So my goal is to try with external, maybe directional panel antenna pointed more or less downward and then check if it helps or not.
If not – then satcom is the only choice for next 10 years until we have something like nextrad.
