BT on meltdown alert as numbers change

Ed Townsend thinks you should sing them. David Edmonds likens them to "moving into a new skyscraper built on to a house". Brian Butterworth warns that you won't be able to remember them. And businesses are furious, claiming they will cost the country £2bn. What everyone is sure of is that they will cause upheaval.

They are the new phone numbers introduced in Britain at about 1am - give or take a couple of minutes - today. The changes are happening over Easter so people have time to get used to them away from work pressures. The alternative would be to start on Tuesday - guaranteeing chaos - or some other day in the working week, which would be even more confusing, say the experts.

So starting now, anyone dialling a local number within London, Cardiff, Coventry, Portsmouth, Southampton and all of Northern Ireland, must dial an extra digit or two before the number, or they will get a recorded message telling them to dial again.

Confusingly, anyone calling from outside those cities can still use the old codes until September, when they will be switched off, creating the strange situation where somebody in Cardiff could still call a London number using the old 0171 or 0181 code, instead of 020 followed by 7 or 8.

Telecoms regulator Oftel has admitted millions of people were unaware of the precise details of the changes, despite a £20m advertising campaign. A survey by BMRB for Oftel a week ago found that only 41 per cent of people gave the right post-change area code, and 37 per cent the right (eight-digit) local number.

The worst day for misdialling is expected to be Tuesday, when most of the population returns to work. People are expected to mess up the code change on every one in four calls, based on the experience of 1995's "PhoneDay", when every code in the UK was changed to begin with "01".

If the proportion of wrong calls is greater, people will get an engaged tone; and if nearly everyone forgets and the system overloads, phones might simply go dead when you pick them up, says Mr Townsend, head of national code and number changes at Oftel. But he thinks the chances of that are minimal. The changes mean Britons now have access to nine billion phone numbers, which Oftel insists will be sufficient for our needs for "at least 15 to 20 years".

But phone use in cities and towns such as Aberdeen, Bournemouth, Bradford, Brighton, Cambridge, Derby, Guildford, Oxford, Preston, Stoke, Wigan and Wolverhampton is growing so fast that they will also require code changes in the next five years.

Mobile and pager numbers are also changing today, though the old numbers will (like the national numbers) run "in parallel" until next April.

But remembering the changes should be quite easy, says Mr Townsend. "There is a sort of music, a rhythm, to phone codes. London codes have their own rhythm, four digits, three digits, three digits; Cardiff ones are four, three, three. What's happening now is that there's a new music about the phone codes."

The change was made possible by the 1995 "PhoneDay" upheaval. That "01" change created the "number space" into which Britain is moving, where there are nine figures after the initial "0". With "00" reserved for international calls, that leaves nine billion numbers for inland Britain, including fixed phones, mobiles, pagers, free and low-rate, premium rate, and some (beginning with 04, 05 and 06) whose uses have not yet been dreamt of.

Mr Edmonds, the director-general of Oftel, calls it "moving into a skyscraper" and says: "When we look back on in three to five years, we will see Britain with the most rational and logical numbering system in the world." New York has 13 different three-digit "area codes" covering the city, followed by seven-digit numbers, limiting it to just 130 million numbers.

Given the rapid growth of faxes and internet connections, that could be swallowed in a few years. London now has 20 million numbers (only half of which are used), and Oftel expects it will be three years before we see the first London code not beginning with 7 or 8.

Logical and rational the changes may be, but Professor Brian Butterworth, a cognitive neuropsychologist at University College London and author of The Mathematical Brain, says the big drawback with eight-digit numbers is that people can't remember them.

"Humans have short-term memory and long-term memory," he says. "You use short-term when you look a number up and have to dial it, or somebody tells you it and you have to write it down. Seven digits is the normal limit for short-term memory - that's something that has been demonstrated and known for 100 years."

Long-term memory of numbers is achieved in two ways, he says. "Either you get it from your short-term memory - if that can hold on to it - or you try to give it structure. The French break their eight-digit numbers into pairs, such as 27, 36, 45, 45. That's four chunks.

"The fact is though that people are going to find it hard to cope with this. If you want an experiment, try to remember your mobile number and a friend's mobile number. Very few people can recall both."

The Federation of Small Businesses (FSB) and the CBI, estimate the costs to businesses at £2bn. The FSB estimated last year that making the changes would cost £500 for someone working from home, and £2,000 for a larger firm.

Mr Edmonds challenges the CBI estimates and adds: "The cost we have seen have been virtually nil, because paper just has a natural life anyway.

"Perhaps this is the time for those businesses to think that instead of having printed stationery, they should just use word processing, where you can change the number with a couple of keystrokes."