UK area code 020 is London. A number beginning with 020 8793 is probably served by BSkyB Telecommunications, and could be anywhere in the greater London 020 area. Further, with number portability, any specific number could be served by any provider.
UK telephone area code 020 (or +44 20 in international format) serves the greater London area, including the areas formerly designated "inner London" and "outer London." A number beginning with 020 8509 is most likely a BT landline in Walthamstow; however, with number portability, any specific 020 number could be located anywhere in the London 020 area, served by any local telephone company.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
UK telephone area code 020 (or +44 20 in international format) serves most of greater London. A number beginning with 020 8603 is most likely a BT landline in Croydon; however, with number portability, any 020 number could be located anywhere in the greater London 020 area, served by any local telephone carrier.
(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but North America (USA, Canada, etc.) uses 011, Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
London is area code 020.
UK area code 020 is London.
A UK telephone number like (020) 84xx xxxx will be in London. You need to state two more digits in order to be able to work out which part of London; eg. (020) 8484 or (020) 8411 etc.
UK area code 020 is London, but there are no valid numbers beginning with 020 4, much less 020 43. Also, the area code for London is just 020, not 020x or 020xx. There are no other UK telephone area codes beginning with 020.
020 is London. 020-3 numbers can be anywhere in London. The operator who "owns" this number is Frontier Systems. Note that the area code for London is just 020, not 0203 or 0207 or 0208.
In the UK, area code 020 is London. A number beginning with 020 8488 could be located anywhere in the 020 London area. It is not possible to specify the location more specifically.
UK telephone area code 020 is London and surrounding areas. It is not possible to narrow down the location any further with the information given. Furthermore, with number portability, any specific 020 number could be located anywhere in the greater London 020 area.
Area code 020 is London. There is no more specific geographic information possible from the information in your question.
Bromley is covered by the area code for London, which is 020.
In the UK, area code 020 is for landlines in London. 84 would be the first two digits of an eight-digit local number.
In the UK, area code 020 is London. There is no area code 0208.
UK telephone area code 020 is London, including both the former "Inner London" and "Outer London" zones. A number beginning with 020 7485 is most likely a BT landline in Kentish Town, but with number portability any particular 020 number could be located anywhere in the greater London 020 zone, served by any local telephone company.