We might occasionally ride our English brethren, but of course we only tease the ones we love. As for today's terrorist attacks in London, we can offer only the thin comfort that we hope everything's alright for you and yours.
If you're trying to make calls into London right now, you might give them a few hours to deal with the understandable confusion. Most of the mobile network switches are overloaded, and some carriers like Vodafone are routing out customer traffic to ensure that police and rescue communication can get through without issue. There is a rumor that the cellular networks have been shut down to prevent the possible detonation of more bombs, but from the statements made from the telephone companies, I don't think that's the case. Either way, take a breath if you can, step back, and give everyone in London a few hours to sort through the first steps of this mess.