Sometimes it is only when the niggling pain goes away that you realise just how irritating and distracting it had become.

A sore tooth can sit for weeks just beneath the threshold of consciousness before you finally decide to do something about it, and you leave the dentist full of optimism, hope and love for all humanity now that you can think clearly.

Well, like a man who bangs his head against a brick wall because it feels so good to stop, I've finally given up grubbing around for open wireless connectivity on the move and invested in a 3G modem for my laptop.

No more will you find me wandering down dark alleyways in search of an elusive open network, or hoping that the train slows down long enough on the run into Stevenage station for me to pick up "Netgear", "default" or "belkin54g" long enough to download my e-mail.

I have to admit that this change of heart has not come about because such activity might be illegal, since I firmly believe that simply joining an open network should not be considered a crime.

The law has clearly not kept match with the capabilities of the technology especially since many people leave their networks open in order to offer a service to passers-by.

And an iPhone or iPod Touch will automatically connect to "known" networks, so if my home network is called "default" I'll join any other open "default" network as I walk the streets.

So I'm confident that a well-constructed defence would establish that the previous convictions under the Communications Act were not justified.

But now I won't even be tempted to latch on to other people's wireless, because I have a little white box, called a dongle, that plugs into a USB port on my laptop and can connect to the phone network.

It works on the train, it works in my favourite (wi-fi-less) cafes in Cambridge and it works in my car sitting by the side of a B-road trying to figure out where I am on Google Maps.

I've been able to get my e-mail and surf the web on my phone for ages, but it has always been a second-best solution, and I'm unwilling to shell out for an iPhone even if the user interface does solve many of the problems I've had with small screens.

But since I have my laptop with me nearly all the time I don't need to compromise on a small screen or inadequate keypad.

New generation

And life is good.

The toothache has been sorted. The ringing in my ears has stopped. I can breathe freely and that sharp pain whenever I bend over sideways has finally cleared up. I can be online whenever and wherever I want to be, and life is good.

The new generation of data modems are already being sold as an alternative to slow broadband for home PCs when ADSL over copper wires is either not feasible or just unreliable.

And it can't be long before someone realises that the external dongle isn't really needed, and offers a laptop with a built-in 3G modem and a slot for a SIM card.

It isn't a perfect service, as I found out last weekend when I tried to stream video from the re-opening of Wysing Arts Centre in the middle of the Cambridgeshire countryside.

You really need a 3G connection for anything at all substantial, and when the connection falls back onto the old GSM/GPRS network it can cope with e-mail but little else.

But it is a viable alternative to wi-fi in cities. As well as being a lot cheaper it lets you move around without dropping the connection because it uses the cellular network.

I can also see how these 3G services could be used in countries without an established telecommunications infrastructure.

Many cybercafes in African countries already use a cellular phone to provide access to the internet, but these dongles could improve the speed and quality of service without needing several phone handsets.

When I first got an always-on internet connection from home I couldn't believe how liberating it was.

This was in the days before home broadband and involved rather a lot of complex fiddling to get SSH tunnelling going over a pair of Centrex lines into a small Linux box on my desk, and if that means anything to you then you've been in this business too long.

Now I'm finding the same sense of freedom comes from having easy, fixed-price access on the move.

Instead of deciding whether to shell out £5 for an hour's access in the railway station or risk the quality of coffee in a well-known fast-food chain just to get free access I can plug in and go.

Once again, the technology has demonstrated its ability to surprise me, and yet again I realise that we are only at the beginning of the transformation which began with the early networks of the 1960s.

Bill Thompson is an independent journalist and regular commentator on the BBC World Service programme Digital Planet.