I think it's the 3 network - I believe they are all locked to a network as presumably Dell has to give them a percentage of the user fees. Could I use it in France, do you know? Dell only seems to offer this on its more expensive laptops - Lenovo have a similar system on cheaper ones.
Dell Studio1558 with Win7 Home Premium 64bit 8GB RAM
IE9 and Live Mail
BT Infinity via HH3