020 4621 3509
Also shown as:
- 020 4621 3509
- +44 20 4621 3509
AI Summary
Based on 2 community reports
This London-based number appears to be making calls claiming to be from O2, stating that your SIM card will be blocked. Both reports describe suspicious behavior, as the callers had no specific information about the accounts they were contacting. With a spam score of 85/100 and no upvotes on the reports, it’s clear this number is potentially used for phishing attempts. If you receive a call from this number, it’s best to hang up immediately and avoid sharing any personal information.
2 verified reports
Cumulative spam score based on all reports up to each month. Higher percentage means higher reported scam risk. Cumulative spam score based on all reports up to each week. Higher percentage means higher reported scam risk. Cumulative spam score based on all reports up to each day. Higher percentage means higher reported scam risk.
Most helpful reports
2 totalsaid they were from O2 and that my sim was going to be blocked, despite knowing nothing about my account, fishing for details. Very suspect.
Said it was from 02 and that my SIM card would be deactivated. I replied... go ahead and block it. Then I ended the call.
Share Your Experience
Help others by reporting what happened
About 020 4621 3509
What type of number is 020 4621 3509?
The phone number 020 4621 3509 (also written as +44 20 4621 3509) is a UK landline number originating from the London area in Greater London . Calls to this number are charged at standard UK landline rates, usually included in call packages.
Is 020 4621 3509 safe to answer?
Based on 2 community reports, this number has been frequently reported as spam or a potential scam. The current risk score is 85% with 2 reports marking it as spam .
Exercise extreme caution if you receive a call from this number. Do not share personal or financial information.
More on nuisance calls
Safety Score
Details
- Tel Number
- 020 4621 3509
- Country
- 🇬🇧 United Kingdom
- Network
- Colt Technology Services
- Area
- London
- Type
- Geographic
- First Seen
- 21 Jan 2026
Protection Guides
How to Block This Number
Step-by-step instructions for iPhone, Android, and landlines
Caller ID Spoofing
Scammers can make any number appear on your phone, including your bank's real one. How spoofing works, how to spot it, and what to do if your own number is being used.
Report to Ofcom
How to report nuisance calls officially
Location
London, United Kingdom
This number originates from the London area code region. The map shows the general geographic area, not an exact location.
Call Types
Breakdown of reported call reasons. Larger segments and bars represent a bigger share of reports.
Is this your number?
Claim ownership to manage reports
We'll verify ownership via callback or documentation