By reading closer the service descriptions and contracts I get that all cheaper offers for unlimited 3G, actually some sort of sub–EDGE offer once one reaches the given 1 or 3Gb limit, they are all made for using into a phone. Putting the SIM into another device, like a USB modem or WiFi HotSpot, would be a breach of contract and reason to close the line.
I've read about guys doing it without restriction. But I also know the system always knows of this.
So do you know a very cheap, if not cheapest, unlocked phone I can get in France that does not have an issue and is recognised by Linux as a modem out of the box, by just pushing in the cable?
Also, can you point out a webpage somewhere about the initiation strings and how to start the ppp connection? Are there any particularities that you know about with the French operators? There is no restriction on language on those pages, they can even be in Swiss French ;-)
I already have a Nokia 2730, but it's locked on a foreign network. And from my experience Nokia does have a lot of deviations from the standard.