- Prefix
020 4- Area
- London
- Number type
- Geographic landline (01/02)
- Format
020 4XXX XXXX- From abroad
+44 20 4XXX XXXX- Ofcom blocks in range
- 200
- Blocks in service
- 154
- Range holders
- 49
What are 020 4XXX XXXX numbers?
Any UK number matching 020 4XXX XXXX sits in the
020 dialling code for London.
Ofcom hands these numbers to communications providers in blocks; this range
contains 200 blocks, of which
154 are allocated and usable. Calls from these
numbers are typically homes and businesses in the London area — or
organisations elsewhere that keep a local 020 presence using
VoIP.
Who holds 020 4… number ranges?
| Range holder (allocated by Ofcom) | Number blocks | Example range |
|---|---|---|
| Colt Technology Services | 38 | 020 4510 XXXX |
| Gamma Telecom Holdings Limited | 26 | 020 4509 XXXX |
| BT | 25 | 020 4505 XXXX |
| Voxbone SA | 8 | 020 4525 XXXX |
| Hyperoptic Ltd | 4 | 020 4503 XXXX |
| Twilio Ireland Limited | 4 | 020 4538 XXXX |
| Verizon UK Limited | 3 | 020 4507 XXXX |
| IOVOX Limited | 2 | 020 4633 XXXX |
| Magrathea Telecommunications Limited | 2 | 020 4502 XXXX |
| TELNYX UK LIMITED | 2 | 020 4520 XXXX |
| Voiceflex Limited | 2 | 020 4553 XXXX |
| 24 Seven Communications Limited | 1 | 020 4595 XXXX |
…and 37 more providers hold smaller allocations in this range.
Ofcom’s data shows the provider each number range was originally allocated to — not who holds an individual number today. Numbers are frequently moved (ported) between providers, and no public database reveals the person or business behind a specific number, so treat any service that claims to with suspicion.
Not every block in this range is in service: of the 200 blocks Ofcom lists, 40 are protected (reserved by Ofcom and not in use) and 6 are free/unallocated. A call appearing to come from an unallocated block is a strong sign of a spoofed number.
How often is 020 4… checked?
28 people checked a 020 4… number with this tool in the four weeks to 20 September 2026. That makes it the 3rd most-checked 020 London range on this site out of 239 with any checks at all.
Checks per week (weeks ending on the dates shown). Our own lookup data, counted once per person per number per day, with Ofcom’s drama/example ranges excluded and refreshed weekly. It measures how many people were curious enough to check a number in this range — it is not a count of scam calls, and it says nothing about any individual number. The quarterly nuisance-call prefixes report puts every range side by side.
Is a call from a 020 4… number safe?
A local-looking number is never proof of who is calling: fraudsters spoof 020 caller IDs so their calls look like they come from London (‘neighbour spoofing’). If an unexpected caller asks for personal, banking or one-time-code details, hang up and ring the organisation back on a number you find independently. To put a name to a caller, see who called me?; to report one, see how to report a scam number.
Check a specific 020 4XXX XXXX number
Paste any full number into the checker above (or on the main phone number checker) to see its exact range holder and allocation status from this week’s Ofcom data.
More 020 number ranges
Full 020 London area-code guide › · All UK area codes › · Nuisance-call data & reports ›