Hi I have just bought a MIFI thingy
You`ll need the APN setting for your current UK mobile/data network, and the
APN setting for mobile/data network in whichever country your using your Mi-Fi
In my case there`s a Huawei app that I can use in my iPhone to connect to, and change the settings in my Huawei Mi-Fi
French phones etc are not locked to a particular carrier, but I presume you bought your device in the UK in which case a French SIM won't may not work.
dc unlocker is what I used to unlock my Huawei Mi-Fi.
The service isn`t free & iirc cost me €7 to do. but using the Dc Unlocker software you can check the lock / unlock status of the Mi-Fi
There are (DC-Unlocker) tutorial videos on youtube to show you how to do it
Anyone with an out of contract iPhone who is/was on the
O2 network can have them unlocked for free.
Anyone who isn`t on O2 just borrow a mates O2 SIM
In France you'll have to provide proof of identity and address before you can buy a sim.
The same problem I had with my Spanish and Portuguese data SIM cards, more so the Spanish SIM but I managed to find a seller on eBay who could sell me a SIM and register it using my (fake) passport number. I was then able to setup and manage my accounts with the mobile company