Quick answer
0203 and 0204 are London numbers. London has one dialling code, 020, followed by an eight-digit number; the 3 or 4 is simply the first digit of that local number, like the older 7 and 8. A call from an 020 3 or 020 4 number costs the same to return as any other 01 or 02 landline call. The digits do not tell you which part of London the caller is in or which organisation it is, and the number on your screen can be faked.
A missed call from 0203 or 0204 looks unfamiliar to anyone who grew up with 0207 and 0208, and that unfamiliarity is why so many people look these numbers up. This guide explains what the numbers are, what Ofcom's own data says about who holds them, how often people check them with our tool, and how to work out whether the call was genuine.
Is 0203 or 0204 an area code?
No. Ofcom describes London as "the capital, whose dialling code is 020", with numbers allocated across the (020) 3, 7 and 8 ranges and, since 2019, (020) 4. Everything after 020 is the local number.
The confusion is old. London had two codes, 0171 for inner London and 0181 for outer London, until 2000, when it was given the single code 020 and the inner and outer divide was removed. Many people carried on reading the new numbers as "0207" and "0208". Ofcom's own research in 2005 found that only 13% of people, without prompting, identified 020 as London's single area code.
Two more ranges have been added since:
- 020 3 numbers were given out from the autumn of 2005. Ofcom's guidance at the time put it plainly: "when you see an (020) 3 telephone number, it's a London number, just like (020) 7 and (020) 8 - and of course the cost of a call is the same."
- 020 4 numbers followed in 2019. Ofcom announced 10 million new London numbers on 30 August 2019, because fewer than a million of the existing 30 million were left to hand out. Phone companies could apply from 1 October 2019 and Ofcom expected customers to start receiving the numbers from December 2019.
Who holds 020 3 and 020 4 numbers?
Ofcom allocates numbers to phone companies in blocks of 10,000 and publishes the list every week. In the files published on 4 November 2026:
| 020 3 | 020 4 | |
|---|---|---|
| Blocks Ofcom lists | 1,000 | 200 |
| Allocated to a phone company | 921 | 155 |
| Protected (reserved by Ofcom, not in use) | 73 | 40 |
| Phone companies holding at least one block | 169 | 49 |
| Largest holders | BT (230 blocks), Gamma Telecom Holdings (138), Colt Technology Services (77), Sky UK (56), Verizon UK (42) | Colt Technology Services (38), Gamma Telecom Holdings (27), BT (25), Voxbone (8) |
Three things follow from that table.
First, there is no single owner to look up. An 020 3 number could sit with any of 169 companies, and each of them passes numbers on to its own customers.
Second, the holder is not the caller. Ofcom's files show the company each block was allocated to. They do not show who uses an individual number, and a number can be moved to another provider and keep its block.
Third, a call that shows a number from a block Ofcom lists as protected or free cannot be coming from a real line in that block. That points to a faked caller ID. The same goes for 020 7946 0000 to 020 7946 0999, the London range Ofcom keeps for TV and radio drama.
Our range pages for 020 3 numbers and 020 4 numbers list the holders in full and are rebuilt when Ofcom's files change.
How often are 0203 and 0204 numbers checked?
A lot, for landlines. In the four weeks to 8 November 2026 people made 744 checks of 01 and 02 numbers with our phone number checker, and 198 of them were London numbers:
| Range | Checks in four weeks |
|---|---|
| 020 3 | 88 |
| 020 8 | 56 |
| 020 4 | 27 |
| 020 7 | 23 |
020 3 was the most-checked landline range anywhere in the UK on our tool in that period, out of 315 landline ranges with at least one check. Its weekly counts were 11, 21, 29 and 27.
These are counts of checks, one per person per number per day. They show which numbers make people curious enough to look them up. They are not counts of scam calls and they say nothing about any single number.
Is a call from 0203 or 0204 a scam?
Not because of the number. 020 3 and 020 4 numbers are ordinary London landline numbers, used by homes, businesses and organisations that want a London number. An 020 number shows the number was issued for London. It does not prove the caller is sitting there, because internet phone services let a business answer an 020 number from anywhere.
Scam callers use London numbers too, either real ones or spoofed ones, because a London landline looks like a head office. So judge the call, not the code. The warning signs are the same on any number: pressure to act at once, threats, a request for a PIN, password or one-time code, or an instruction to move money. Our guide to checking whether a number is a scam sets them out.
What does it cost to call back?
The same as any 01 or 02 number. Ofcom's call costs guide gives typical charges for geographic numbers of up to 16p a minute from a landline, often with a 23p call set-up fee, and between 3p and 65p a minute from a mobile when the call is outside your inclusive minutes. Most plans include these calls. There is no premium charge on an 020 number.
What to do about an unexpected 0203 or 0204 call
- Let it go to voicemail. A genuine caller usually leaves a message saying who they are.
- Check the full number with the free phone number checker. It confirms the number is a London landline and shows the phone company Ofcom allocated its block to.
- Search the full number in quotes. A business usually publishes its own number, and nuisance numbers are often reported by other people.
- Call back on a number you find yourself if the caller claimed to be your bank, a government department or a company you deal with. For your bank, dial 159.
- Block and report a number that turns out to be a nuisance - see how to block unwanted calls and how to report a scam number.
The bottom line
0203 and 0204 are London numbers under the single 020 code, added in 2005 and 2019 as the older ranges filled up. They cost no more to call than any other landline, they can be used anywhere in London, and Ofcom's data ties each block to a phone company and never to a caller. Check the full number, look for a voicemail, and decide on what the caller asked for.
Sources
- Ofcom, press release of 30 August 2019, "London calling: Ofcom to release new '(020) 4' phone numbers", read in the copy held by Wired-Gov: the 020 code, the 2000 change, the 2005 research, the 10 million new numbers and the dates, and allocation in blocks of 10,000.
- Ofcom, "The London Area Code" guidance, read in the Internet Archive copy: the introduction of (020) 3 numbers from autumn 2005.
- Ofcom, Download numbering data: the block allocations published on 4 November 2026, as shown on our range pages.
- Ofcom, Call costs guide (last updated 31 January 2025): typical charges for 01 and 02 numbers.
- Ofcom, Telephone numbers for use in TV and radio drama programmes: the London drama range.
- Our own figures: checks made with the phone number checker on this site in the four weeks to 8 November 2026.
All five pages checked on 10 November 2026.
Frequently asked questions
Is 0203 a London number?
Yes. 0203 is the London code 020 followed by a local number beginning with 3. Ofcom has issued 020 3 numbers since 2005, and they can be used anywhere in London. The correct way to write one is 020 3XXX XXXX.
Is 0204 a real area code?
0204 is real, but it is not an area code of its own. It is the London code 020 followed by a local number beginning with 4. Ofcom announced the 020 4 range on 30 August 2019 and expected customers to start receiving the numbers from December 2019.
What is the difference between 0203, 0204, 0207 and 0208?
Only the first digit of the local number, and roughly when the number was first issued. All four are London numbers under the 020 code. Before 2000, 0171 was inner London and 0181 was outer London; that split was removed when 020 was introduced, and 020 3 and 020 4 numbers have never been tied to a part of the city.
Does it cost more to call an 0203 or 0204 number?
No. It costs the same as any other 01 or 02 landline number and is normally included in your inclusive minutes. Outside an allowance, Ofcom's call costs guide gives typical charges of up to 16p a minute from a landline and between 3p and 65p a minute from a mobile.
Can I find out who owns an 0203 or 0204 number?
You can find the phone company Ofcom allocated the block of numbers to, using the free phone number checker, and a web search of the full number often finds the business that publishes it. No public record names the person or business behind an individual number.
Why do I keep getting calls from 0203 numbers?
020 3 is the largest of the newer London ranges, with 921 blocks of 10,000 numbers allocated to 169 phone companies in Ofcom's files of 4 November 2026, so a great many lines ring out from it. It was also the most-checked landline range on our tool in the four weeks to 8 November 2026. Repeated calls that leave no voicemail often come from an automated dialler; block the number and see how to stop nuisance calls.
