London phone numbers
0203 numbers are all part of the 020 area code for London and the surrounding area.
London has had the area code 020 since the year 2000. This is followed by an eight-digit local number.
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
020 or 0203?
The area code for London is simply 020; the following digits are all part of the eight-digit local number.
The 020 area code at the beginning is optional; calls from one London landline phone to another can be made using just the eight-digit local phone number.
» 020 area code
Full details of areas covered and the history of 020 numbers.
» Phone number formatting
How to correctly display phone numbers for major UK cities.