One thing that annoys me more than persistent nudging is the London telephone number.

In its own way, this simple string of 8 or 11 numbers demonstrates that when we look into the future we rarely look that far.

It's not the number's fault that I get so angry. It's telecoms regulator Oftel's short-sightedness and others' ignorance.

The London phone number has changed many times in recent years. It was easy when it was 01 for London. Then we got 071 (inner London) and 081 (outer London) before 0171 and 0181. Then that changed to 020. As a transition Oftel squeezed in another inbetween. 0207 and 0208 were meant to get us used to dropping the 01 altogether, but it was only meant to last a few months.

But what happened was that most people stuck with 0207 or 0208. And that's what gets me mad.

Why? Because the dialling code is not 0207 or 0208, it's 020. So if you say your phone number is 0207 0713620, you're giving out the wrong number. It doesn't matter if someone dials that whole number, but if your caller is also based in London he won't need the dialling code and should then call 07713620. He'll get an engaged tone and never an answer.

I even spoke to a BT employee once who insisted that my dialling code was 0207. And you see this on company stationery, business signs and on the sides of vans all over the capital.

Oftel kept changing numbers because it foresaw an enormous need for thousands of new lines in the future, where everything was based around the telephone line. Everybody would have a fax machine, and dialup modems would be in every house, if not every room!

Ringing the changes

London’s 01 code was on the verge of running out of local numbers in the late 1980s, so the capacity was doubled in 1990 by splitting the area into two – inner/outer London, using the codes 071 and 081. This didn’t give London any extra numbers at all. It did create a huge pool of unused numbers - 02 to 09 - for an extra 8 billion numbers for use for other services. The 020 code for London provides five times as many numbers again (10 x the amount of London numbers which existed prior to the 1990 changes) while retaining local dialling across the whole London area.

A study carried out for Oftel in 1996 concluded that London would need, at most, 30 million numbers to meet likely demand up to 2012. The 020 change provided an extra 64 million numbers to make 80 million in all.

But today looks a little different from Oftel's future vision. The fax machine is obsolete. Broadband (using the same phone line as the telephone) has crushed the modem and need for a second or third line. And an increasing number of people rely on mobile rather than land lines for their daily natter needs.

Far from needing 30 million new numbers we could probably lose the odd 10 million and never notice. So next time someone tells you that changes are required based on far-off projections, ask them if they've really looked into the future at all.