In the UK, it's illegal to use a phone while driving unless it is completely hands-free. Doesn't stop idiots doing it, and I don't agree with the hands-free option, but there you go. I spend a lot of time in the US (lived there for 11 years) and have lived in the UK for the last
5 years. My impression is that mobile phone use is more prevalent here in the UK- not least because of the more attractive PAYG market. On my last trip to the US, I couldn't even get a GSM signal within two miles of where I was staying, 30 miles outside NYC. That would be pretty rare in the UK.