O2 (Telefonica) Spam Calls — UK Numbers Most Reported on Our Checker
Ranking of the O2 (Telefonica)-allocated UK numbers most-looked-up on our free UK Phone Number Checker. These rankings reflect public lookup interest, which strongly correlates with scam / nuisance call reporting. Currently tracking 2,534 distinct numbers across 4,402 public lookups.
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Top-looked-up O2 (Telefonica) numbers
Click any number to see its full lookup page with risk-level, range holder, community reports and related numbers.
| Number | Searches | Last looked up |
|---|---|---|
| 07394 51**** | 81 | 3 Jul 2026 |
| 07510 24**** | 24 | 20 Jun 2026 |
| 07395 48**** | 19 | 24 Jun 2026 |
| 07512 42**** | 19 | 29 Jun 2026 |
| 07354 69**** | 17 | 29 Jun 2026 |
| 07395 57**** | 17 | 29 Jun 2026 |
| 07394 10**** | 16 | 2 Jul 2026 |
| 07395 27**** | 16 | 26 Jun 2026 |
| 07395 36**** | 16 | 26 Jun 2026 |
| 07395 45**** | 16 | 26 Jun 2026 |
| 07395 60**** | 16 | 26 Jun 2026 |
| 07394 57**** | 15 | 24 Jun 2026 |
| 07394 66**** | 15 | 24 Jun 2026 |
| 07395 06**** | 15 | 1 Jul 2026 |
| 07395 73**** | 15 | 29 Jun 2026 |
| 07499 15**** | 15 | 27 Jun 2026 |
| 07354 16**** | 14 | 22 Jun 2026 |
| 07394 07**** | 14 | 2 Jul 2026 |
| 07395 47**** | 13 | 1 Jul 2026 |
| 07514 67**** | 13 | 29 Jun 2026 |
About O2 (Telefonica) in the Ofcom register
O2 (Telefonica) is one of the UK communications providers allocated number ranges by Ofcom under the National Telephone Numbering Plan. Number allocations are recorded against the legal entity Telefonica UK Limited. Numbers within those ranges may now be in active use by the original allocated subscriber, may have been ported to another carrier under UK number portability rules, or may have been re-issued after being returned to the operator's pool — so the Ofcom range holder is not a guarantee of the current call source.
O2's UK number allocation
Ofcom has allocated 1,629 number blocks to Telefonica UK Limited. Each block is typically 1,000 or 10,000 consecutive numbers. The mix below shows what kinds of numbers O2 runs — useful context for judging whether a call claiming to be from O2 is plausible.
| Number type | Allocated blocks | Share |
|---|---|---|
| Mobile (07) | 1,612 | 99% |
| Freephone & special-rate (08) | 13 | 1% |
| Service & access codes | 2 | 0% |
| Geographic landline (01 / 02) | 1 | 0% |
| UK-wide non-geographic (03) | 1 | 0% |
Are O2 numbers safe to answer?
Usually, yes — the vast majority of calls from O2-allocated ranges are ordinary, legitimate calls. But a number sitting in a O2 range is not a guarantee of safety: fraudsters routinely spoof or hijack numbers from every major UK operator, and porting means a number may no longer be on O2's network at all. Judge each call on what's actually said: never hand over bank details, passwords or one-time security codes to an unexpected caller, and if in doubt hang up and call the organisation back on a number you have verified independently.
How to block and report unwanted O2 calls
Block or report an unwanted number
- You can block an unwanted number directly from your recent-calls list on iPhone or Android, and forward scam texts free to 7726.
- Scam or fraud calls should be reported to Action Fraud (0300 123 2040) or Police Scotland (101); persistent marketing calls to the ICO / TPS.
Full step-by-step instructions for every phone, network-level blocking and all UK reporting routes are in our guide: How to block and report unwanted calls in the UK.
How to stop unwanted calls for good
Blocking O2 numbers stops that one number, but determined nuisance callers simply switch numbers. Silencing unknown callers, enabling your network's free spam shield and registering with the TPS cut the volume across the board — our canonical guide walks through each step: How to block and report unwanted calls in the UK.
Frequently asked questions about O2 numbers
Are O2 (Telefonica) numbers always genuine?
No. While O2 (Telefonica) is allocated UK number ranges by Ofcom, scammers commonly spoof or hijack numbers from any UK operator's range. A number being in a O2 (Telefonica)-allocated block does not guarantee the caller is O2 (Telefonica) or O2 (Telefonica)-owned.
How do I report a O2 (Telefonica) spam call?
Forward spam SMS messages to 7726 (free of charge — works for all UK mobile networks). Report unsolicited marketing calls to the Information Commissioner's Office (ICO) at ico.org.uk/concerns. If you lost money to a scam call, report to Action Fraud at actionfraud.police.uk or 0300 123 2040.
How do I block a O2 (Telefonica) number?
On iPhone, tap (i) next to the number in Recents and choose Block this Caller. On Android, long-press the number and choose Block / Report spam. To prevent unknown callers ringing through, enable Settings → Phone → Silence Unknown Callers (iPhone) or your dialler's spam filter (Android).
Why are some O2 (Telefonica) numbers reported as scam more than others?
Fraudsters target ranges they know are widely allocated, so the volume of reports per O2 (Telefonica) number reflects the size of the active block more than O2 (Telefonica)'s own conduct. Numbers in newer or larger ranges naturally see more reports purely on volume.
Check another UK number
Or use the free UK Phone Number Checker to look up any UK number — the result shows the Ofcom range holder, risk level, and any community reports on file. You can also add your own report directly on the checker results page.