What is the area code for the North West of London?

Answer 1

The area code for the whole of London is 020. This is then followed by an eight-digit local number.

Note that sometimes people in London confuse the distinction between the area code and the local number, and misquote their code as "0208" or "0207".

From outside the UK, area code 020 becomes +44 20.

(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.)
Dial your International Access Code (011 from US; 00 from much of Europe; etc).

Dial the UK Country Code (44).

Dial the Area code, omitting the leading zero (London 020 becomes 20, etc).

Dial the four to eight digit local number.

For example, a Portsmouth number 023 9211 2222 would be dialled from abroad as +44 23 9211 2222.

Answer 2

The telephone area code for all of London is 020, which is +44 20 in international format.

Although you will often see incorrect references to area codes 0207, 0208, and 0203, the correct area code is just 020, with 8-digit local numbers.

(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.)