Don’t buy an O2 SIM in England if you also want to use it in France. While on holiday I was assured by the O2 salesman in England that it would be possible to be used in both countries. However it didn’t , and I had to purchase another SIM for use while in France. Also, in England the WIFI cut out a few times and had to re-boot the phone to get it going again. Stick with one of the better known providers.