The 0203 code, to be introduced in London next summer, is the former prefix for numbers in and around the West Midlands city.

A third London code is intended to meet demand for 400,000 new numbers in the capital every year. It will operate alongside, rather than replace, 0207 and 0208 and will be allocated across Greater London in the hope of eliminating the snobbery that accompanies distinctions between inner and outer zones. But there are concerns that holders of 0203 numbers will be sneered at as nouveaux and that those issued with the prefix will suffer an identity crisis.

Coventry has not long dropped the 0203 code and many websites, old business cards and out-of-date phone books still carry it. From next summer, when 0203 becomes a London prefix, there will inevitably be some confusion.

“The London identity is valuable to business — in telephone terms you are defined by being 0207 or 0208,” Dan Bridgett, of the London Chamber of Commerce, said.

“There may be some concern among new entrants to the market that 0203 does not identify them sufficiently strongly with the capital.”

Similar problems arose with the last significant phone number upheaval in 2000 when homes and businesses in Bodmin, Cornwall — where the code had been 0208 — were confused with London homes, shops and offices.

Londoners will also grumble at yet another change to their numbers. Until May 1989, everything in the capital was prefixed 01. Then came 071 and 081, 0171 and 0181 and, in April 2000, 0207 and 0208.

The need for more phone numbers is not just down to economic growth, the internet, multiple occupancy buildings or fax machines.

One problem is that many telephone companies do not recycle numbers after a customer has ceased to use them.

Ofcom, the telecommunications regulator, maintains that the introduction of the new prefix (or “sub-range” in industry speak) will cause minimum fuss. Ed Knight, a spokesman, said: “There is no change to existing numbers and no need for anyone to change their stationery or inform people their number has changed.

“This is about forward planning and anticipating London’s increasing need for telephone numbers.”

However, BT, the biggest phone company, seemed to be taken aback by the announcement. “I’m puzzled, I don’t think we know about this,” a spokeswoman said.

And the saga will not end in London, or Coventry. Ofcom does not want to alarm anyone else just yet, but there are similar changes in the pipeline for other British cities where the supply of numbers is also running out.

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