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High risk
020 7864 6537
AI Summary
Based on 3 community reports
Calls from this London number, which is with Colt Technology Services, report an attempt to scam people by claiming to be from the mobile provider "Three". The callers state that your SIM card will be deactivated within 24 hours and ask for personal details to prevent this. However, reports indicate that the scammers are using this tactic even on individuals who are not customers of "Three", making it a clear indicator of a phone scam. If you receive a call like this, it's best to hang up immediately as they are trying to trick you into giving away sensitive information.
Written automatically by AI from the community reports on this page. It does not set the spam score, and it can make mistakes, so read the reports below as well.
3 moderated reports
Every report is checked before it is published and counted towards the score. How moderation works
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
3 totalSubmitted by users and shown as written, so wording and spelling are their own. Each report is checked before it appears.
Said they were from Three and that my sim would be deactivated in the next 24 hours and they needed to take some details. Told them I didn’t believe them and hung up.
Said they were from THREE and told me my number would be taken off the network in the next 24 hours
Said they were from Three and that the SIM card is being deactivated. I'm not even with Three!!
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Help others by reporting what happened
How this page was checked
This page is generated dynamically from community reports and lookup activity, and changes as new reports arrive. The risk score is based on community reports about calls and texts from this displayed number. It is not based on official records of who owns the number.
- Reports moderated by
- CallerCheck Moderation Team
- Safety guidance reviewed by
- CallerCheck Editorial Team
- AI summary
- Generated from approved community reports only
- Last report received
- 26 Feb 2026
- Last reviewed
- Reviewed automatically from current approved report data
- AI summary last generated
- 02 Sep 2026
- Last materially updated
- 02 Sep 2026
What do these dates mean?
Report and lookup dates come from user activity. Review dates show when CallerCheck last checked the page. We use “last materially updated” only for meaningful page changes, not cosmetic changes.
- First seen:
- when this number first appeared on CallerCheck, through its first lookup or report.
- Last report received:
- the most recent approved community report for this number.
- Last lookup:
- the most recent time a user searched for this number.
- AI summary last generated:
- when the AI summary on this page was last rewritten from the approved community reports.
- Last reviewed:
- the most recent human moderation or editorial review, where available.
- Last materially updated:
- the most recent meaningful change to this page, such as a new report or a change to its score.
Sources and safety guidance
- Community reports about this number, screened before they are published or counted. How moderation works
- Ofcom numbering allocation data for the network this range belongs to
- Safety guidance aligned with UK scam-reporting advice, such as Report Fraud (formerly Action Fraud) guidance, forwarding spam texts to 7726, and the 159 banking helpline where relevant. Where to report a nuisance call
Important limits
Caller ID can be spoofed, so a high risk rating means people have reported suspicious activity involving this displayed number. It does not prove that the registered owner of the number made the call or text. Community reports describe individual experiences and are not official confirmation of a scam. How caller ID spoofing works.
Own or manage this number? If this number belongs to you or your organisation, you can claim or dispute this profile. We review claims, check supporting information, and may update the page if reports appear to involve spoofing, mistaken identity, or outdated information. Claim or dispute this number
About 020 7864 6537
What type of number is 020 7864 6537?
The phone number 020 7864 6537 (also written as +44 20 7864 6537) 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 7864 6537 safe to answer?
Based on 3 community reports, this number has been frequently reported as spam or a potential scam. The current risk score is 80% with 3 reports marking it as spam .
Exercise extreme caution if you receive a call from this number. Do not share personal or financial information.
What this data can and cannot tell you
The reports on this page come from members of the public about calls and texts that showed this number. Caller ID can be spoofed, so the person contacting you may not be the genuine holder of the number, and a legitimate number can be misused. Before paying anything or acting on a message, check the claim with the organisation involved using contact details from its official website or letters, never the ones in the message itself.
More on nuisance calls
Safety score
3 reportsHow this score was worked out
Each report rates the number as safe, unknown, suspicious or spam. The score combines those ratings, giving more weight to clear scams, and each person counts once. A number only reaches high risk once several people have independently reported it. Scores of 70% and above count as high risk, 40% to 69% as medium, and below 40% as low; a low-risk number reads Maybe Safe once someone reports it as safe. More about spam scores
Why this number is rated High Risk
This number is rated High Risk because 3 of 3 reports classify it as spam or suspicious, and several reports describe the same broadband or telecoms scam. No reports identify the number as safe or expected.
Ratings reflect screened community reports, not official records. How the spam score works.
Confidence: Medium
Based on 3 community reports with repeated matching details. Confidence describes how much report evidence sits behind this page, and is separate from the spam score.
Caller ID can be spoofed, so reports may describe misuse of the displayed number rather than the registered number owner.
Details
- Tel Number
- 020 7864 6537
- Country
- 🇬🇧 United Kingdom
- Network
- Colt Technology Services
- Area
- London
- Type
- Geographic
- Coverage
- London and the surrounding area
- Cost to call
- Standard landline rate
- First Seen
- 21 Feb 2026
Network shows the operator this number range is allocated to, which is public information from Ofcom. The caller may be on a different network if the number was moved or spoofed. First Seen is the date this number first appeared on CallerCheck.
What To Do Now
Steps that fit the broadband or telecoms scam pattern reporters describe.
-
1
Do not share personal or payment details
Do not give personal information, card details or security codes to an unexpected caller or message.
-
2
Verify independently
If the caller claimed to be an organisation, find its official contact details yourself and check the claim directly.
-
3
Block and report the number
Stop further contact from 020 7864 6537 and forward scam texts to 7726. How to block a number on any phone.
Already paid or shared bank details? Call your bank straight away using the number on the back of your card, or dial 159 to be connected to your bank securely.
What people say about CallerCheck
“Really useful to look up who’s constantly calling so I can decide whether to pick up, hang up or send to voicemail”
“Free service gave, instant answer gave enough data for me to realise it was probably a scam - hence forewarned I shall not be answering this number should it ring again,”
“Good website. Very easy site to navigate and to leave comments for other users to see.”
Call Types
Breakdown of reported call reasons. Larger segments and bars represent a bigger share of reports.
Location
London, United Kingdom
This number originates from the London area code region. The map shows the general geographic area, not an exact location.
Protection Guides
How to Block This Number
Clear 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
Is this your number?
Claim or dispute this profile
We'll verify ownership via callback or documentation
We review claims carefully and may keep warnings visible where community reports still indicate risk.