There is a common misconception that London had two area codes, 0207 and 0208, and then 0203 was added. As a result, there’s a perceived (incorrect) difference between an ‘0203 number’ and an ‘0207 number’.
This is not the case, London has one area code – 020 – and an eight digit local number e.g, 8125 9999. We offer a wide range of London numbers, starting with a 3, 7, or 8.
To add to (or, perhaps, eventually simplify!) the confusion, Ofcom will release a new block of (020) 4 local numbers from October 2019. These new London numbers will take the form 020 45xx xxxx.
Numbering is a limited resource, and we’re committed to ensuring it is used efficiently. As we still have plenty of capacity in our existing 020 ranges, we won’t be first in line for the new (020) 4 number range, but be assured that these are just standard London numbers wherever you see them; you’ll be able to call them at the same rate as any other geographic number, and as we continue to consume our existing capacity we may start offering London numbers starting with a 4.
Ofcom has asked that all CPs take any opportunities to strengthen [our] customers’ understanding that the area code for London is (020) followed by an eight-digit subscriber number. There is no inner and outer London area code split (this was removed in the year 2000). Helping to reinforce this message will support the introduction of (020) 4 and reduce confusion about the London area code.