[davidtheprof]

1. A Piranha international sim usually has best rates - for France, it's 12c/min outgoing, 6c incoming, and 2c/min on wifi. It will come with US and UK numbers, so you can forward your regular number to this, and give folks in France the UK number to call, much cheaper than a US number. Data is 30c/MB on most networks, 15c on Bouygues.

2. Or get a local French sim, usually on ebay so can set up before. I've also used O2 UK for Europe, data roaming in Europe is something like 2 pounds a day for 15MB, but calls not so cheap - but another mandatory price reduction in Europe after July 1.

3. Or switch to TMobile Simple choice plan in US, then just take your phone, free data (slow but I've found adequate, even for navigation), and calls 20c/min in and out.

With choice 1 and 3, you only have to deal with one phone, no worries about hotspot.

If you do need to tether a laptop, use something like pdanet with USB tether, seems OK