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 1,620 distinct numbers across 2,546 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**** | 44 | 11 Jun 2026 |
| 07395 48**** | 18 | 6 Jun 2026 |
| 07510 24**** | 17 | 11 Jun 2026 |
| 07395 45**** | 15 | 27 May 2026 |
| 07354 69**** | 14 | 10 Jun 2026 |
| 07394 66**** | 14 | 6 Jun 2026 |
| 07354 16**** | 13 | 10 Jun 2026 |
| 07394 57**** | 13 | 6 Jun 2026 |
| 07395 06**** | 13 | 9 Jun 2026 |
| 07395 60**** | 13 | 15 May 2026 |
| 07395 73**** | 13 | 4 Jun 2026 |
| 07512 42**** | 13 | 9 Jun 2026 |
| 07395 57**** | 12 | 11 Jun 2026 |
| 07394 08**** | 11 | 10 Jun 2026 |
| 07395 47**** | 10 | 11 Jun 2026 |
| 07395 65**** | 10 | 25 May 2026 |
| 07354 24**** | 9 | 22 May 2026 |
| 07395 35**** | 9 | 9 Jun 2026 |
| 07394 18**** | 8 | 15 May 2026 |
| 07394 99**** | 8 | 10 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 an unwanted number on your phone
- iPhone: open Phone → Recents, tap the (i) next to an unwanted number, scroll down and tap Block this Caller.
- Android: open the Phone app, press and hold an unwanted number in your recent calls, then tap Block / Report spam.
- Network level: EE, O2, Vodafone and Three all offer free spam-call blocking in their app or online account settings.
Report an unwanted number
- Scam texts: forward the message to 7726 (free) — it spells "SPAM" on the keypad — to report it to your mobile network.
- Scam or fraud calls: report to Action Fraud on 0300 123 2040 (England, Wales & NI) or Police Scotland on 101.
- Nuisance / marketing calls: report to the ICO and register with the free Telephone Preference Service (TPS) to reduce unsolicited sales calls.
How to stop unwanted calls for good
Blocking O2 numbers stops that one number, but determined nuisance callers simply switch numbers. These steps cut the volume across the board:
- Silence unknown callers. iPhone: Settings → Apps → Phone → Silence Unknown Callers. Android: open Phone → Settings → Caller ID & spam and turn on filtering. Unknown numbers go straight to voicemail.
- Turn on your network's free spam shield. EE, O2, Vodafone, Three, Sky and most providers offer free spam/scam-call screening in their app or account settings.
- Register with the Telephone Preference Service (TPS). It's free and legally obliges UK companies to stop unsolicited sales calls within 28 days.
- Use a dedicated call-blocker app if nuisance calls are persistent — these screen against live community spam databases and can auto-reject flagged callers before your phone even rings.
- Never engage to "opt out". Pressing a key to be removed only confirms your number is live and usually means more calls.
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.