Chinese whispers across London airwaves

It is a useful convention in international affairs that anywhere in the world, a country's embassy is its sovereign territory. This covers a multitude of sins and helpful tax breaks, but gets particularly interesting when you consider wireless regulation. Radio waves don't stop at embassy walls – so if the ambassador gets it into their head that they want to start a pirate radio station, there's nothing much to stop 'em.

Normally, of course, nobody wants to make a fuss. It is accepted that embassies will sit there snooping on whatever they can hear from the city around them while transmitting what they like back to base (and, sometimes, to local spies – but that's normally thought of as bad form and is in any case a bit bleedin' obvious).

But in these modern days, the possibilities are greater. What to make of a rumour alluded to by mobile phone industry watcher Cat Keynes, who at the bottom of a posting about Chinese 3G standards, says:

It will be interesting to see what the Chinese do about security. Take a GSM phone to China today and you’ll get a warning that there is no encryption. WCDMA has much better encryption and you can be sure the Chinese authorities will want to be able to intercept calls. Perhaps they will have to rely on listening through the network operator. Of course that’s not an option they have in the UK which might account for some interesting network planning issues around the Chinese Embassy in London. They wouldn’t perhaps be running a phantom cell so that they can listen to calls and read the text messages of the Free Tibet protesters outside would they?

This ties in nicely with a rumour I'd heard, that one of the Free Tibet protesters who stand outside the Chinese Embassy in London phoned a friend who was on their way down to join in the fun. Said friend made a joking reference to coming along equipped to do naughtiness – and moments later, the police turned up and proceeded to nab the original caller. They made it plain that it was because of the call.

And, of course, it's not illegal for the Chinese to run such a cell within their embassy. It's possible, and one would expect it to be probable were such an enterprise in effect, for the cell or cells to be configured to pretend to be the mainstream networks. And if so, who can tell whether there is co-operation with the operators for hand-overs (and, perhaps, putting the phantom cells in the base station databases to fool people with applications which can reveal cell IDs and locations – CellFinder on Android is a very good example)?

So, if you're in the habit of wandering around wthin a few hundred yards of embassies, bear in mind that it is perfectly legal, perfectly possible and perfectly likely for your calls to be intercepted and monitored. GSM encryption? Doesn't matter: that only handles the link between the mobile and the base station. If you're at the base station, you can get the decrypted content – sometimes, with enormous consequences.

Best be careful what you say, eh? Mind how you go.