London – area code 020
In the UK, an '020 3 number' or '0203 number' is a normal landline phone number within the London (020) area code.
Any UK number beginning with 020 is a London number. The '020' area code at the beginning is optional if you're dialling from one London 020 landline phone to another.
0203 or 020?
There is no 0203 area code. London has a single city-wide area code of 020, used with eight-digit local numbers. '0203 numbers' are no different from any other 020 phone numbers.
The correct way to write a number beginning '0203' is
Inner or Outer London?
Although there were separate area codes of 0171 and 0181 for inner and outer London until the year 2000, this distinction was abolished when London went back to having a single London-wide area code. There's now no official difference between numbers starting