020

020 is the national dialling code for London in the United Kingdom. The area it serves, which includes most of Greater London and some adjacent areas, was first allocated the STD code 01 in 1959. After a sequence of changes in the 1990s, culminating with the Big Number Change, the current 020 code became active on 1 June 1999. All subscriber numbers within the area code consist of eight digits and it has capacity for approaching 100 million telephone numbers. The code is used at 170 telephone exchanges as part of the largest linked numbering scheme in the United Kingdom. In common with all other British area codes the initial '0' is a trunk prefix that is not required when dialling London from abroad.