Ofcom will begin introducing 0203 numbers for London businesses from 1 June 2005.
The new codes are needed to meet increasing demands for new numbers, the telecoms watchdog said. Last year the organisation issued 400,000 new numbers in the capital and supplies of existing numbers have begun to run short.
Demand is being driven by the increasing telecoms requirements of business and the rise of multiple occupancy houses in the capital.
Section 63 of the Communications Act 2003 requires Ofcom to seek the best use of appropriate telephone numbers and to encourage efficiency and innovation.
Printers and sign painting firms will be disappointed, however, since existing 0207 and 0208 numbers will remain unchanged.
The stock of existing numbers is expected to run low by 2005 and new numbers will be issued with the 0203 codes, as well as the last 0207 and 0208 codes.
This is the fourth change to the capital's numbering system in 14 years.
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