The info is very hard to find. Short of going into a (rare) dedicated shop,
all the links are dead (the french Tatoo goes back to 95 though).
I only found that in "francs", sending a message (numeric only) costs 3,71.
Roughly half a €, which is a lot to ask to any sender.
Worse, it seems it actually now costs around 2€!
But it's still working, a german company runs the show.
Too bad the costs are so high, it would be a cool thing to have :(
Plus I'm sure it can actually cost much less, just like for text messaging
(which are still overpriced compared to their probable cost to the phone
company).
Oh well, So it's either being reachable, or being geotracked. Tough frankly I
don't really care so much aout my geolocation being available (as long as I
can switch off when I want to).
The true problem is modem isolation. It's like having your internet box
soldered to your computer.