In the UK, telephone area code 020 is London.
A number beginning with 020 7241 is most likely a BT landline in Kingsland Green or Kentish Town; however, with number portability, any specific number in 020 could be anywhere in greater London, served by any local carrier.
Central London.
Actually, the number will in fact be 020 7264.... When spaced correctly like this, it's easy to see that 020 is the area code, which means London within the UK.Within the area code 020, numbers beginning 7264 are allocated to BT for use in Wapping, although of course they could be redirected to anywhere in the world if their owner has chosen to do so!(0207 is not an area code, but people often write numbers wrongly in London if they haven't quite got their head round the last renumbering in the year 2000.)
Clerkenwell
In the UK, area code 020 is London, but there are no numbers beginning with 020 2. Other countries may have similar telephone area codes.
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.
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.
149.25
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.
UK telephone area code 020 is greater London. A number beginning with 020 8262 could be located anywhere in the greater London 020 area; that prefix is not associated with any particular borough, district, or neighbourhood. Furthermore, with number portability, any 020 number could be located anywhere in greater London, served by any local telephone company.
In the UK, telephone area code 020 is London. A number beginning with 020 3432 is a "virtual" number that could be anywhere in London. Furthermore, with number portability any specific 020 number could be located anywhere in the London area, served by any local phone company.
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.
There is no area code 0208 in the UK. The area code for London is just 020, with 8-digit local numbers. A number beginning with 020 8749 is most likely a BT landline in Shepherds Bush, but with number portability any specific 020 number could be located anywhere in London, served by any local phone company.
UK telephone area code 020 is greater London. For a number beginning 020 3553, it is not possible to narrow down the location any further, even as to the old "inner/outer" London division. It could be anywhere in greater London.