How to Report SIM Swap Fraud to Your Bank and Telco in Nigeria
Imagine reaching for your phone and discovering that your SIM card has suddenly lost network service. You restart the device, remove and reinsert the SIM, but nothing changes. Shortly afterwards, you discover unauthorised transactions on your bank account.
This could be a sign of SIM swap fraud.
SIM swap fraud occurs when criminals gain control of a person's mobile number by fraudulently transferring it to another SIM card. Once they control the number, they may receive SMS messages, banking alerts and one-time passwords (OTPs) intended for the legitimate owner.
Because many Nigerians use their phone numbers for banking authentication and account recovery, an unauthorised SIM swap can expose multiple financial and digital accounts.
One common mistake victims make is reporting the incident to only their bank or only their telecom provider.
Both institutions need to be contacted because they are responsible for different parts of the problem. Your bank must help protect your money and investigate suspicious transactions, while your telecom provider must investigate the unauthorised SIM replacement and restore control of your number.
Here is how to report SIM swap fraud in Nigeria and what to do if you suspect your number has been compromised.
What Is SIM Swap Fraud?
SIM swap fraud is a form of identity theft in which criminals manipulate a mobile network operator into transferring a victim's phone number to a different SIM card.
The fraudster may use stolen personal information, social engineering or fraudulent identity verification to convince the telecom provider that they are the legitimate owner of the number.
Once the transfer is completed, the victim's original SIM may lose network service while the criminal receives calls and SMS messages sent to the number.
This can create opportunities for criminals to:
Receive banking OTPs and verification codes.
Reset passwords on accounts linked to the phone number.
Access financial applications.
Intercept account security alerts.
Attempt unauthorised transfers and other financial transactions.
The Nigerian Communications Commission (NCC) warns that SIM swap scams can expose banking and other digital accounts when criminals gain control of a victim's mobile number.
How Do You Know Your SIM May Have Been Swapped?
A sudden loss of network signal does not always mean SIM swap fraud. It could be caused by network outages, damaged SIM cards or temporary service problems.
However, certain warning signs should be taken seriously, especially when they occur together.
1. Your SIM suddenly loses network service: Your phone displays messages such as No Service or Emergency Calls Only, even though other users on the same network have coverage.
2. You receive unexpected SIM replacement notifications: Your network provider may send a message indicating that a SIM replacement or account change has been requested.
3. You stop receiving banking alerts: Transaction notifications and verification messages may suddenly stop arriving.
4. You receive unexpected password-reset notifications: You may receive alerts about login attempts or password changes that you did not initiate.
5. You notice unauthorised transactions: Money may leave your bank account or digital wallet without your approval.
6. Your mobile number stops working: Calls and messages may no longer reach your original SIM because the number has been transferred.
If you suspect an unauthorised SIM swap, do not wait until money disappears before taking action.
What to Do Immediately If You Suspect SIM Swap Fraud
Before going through the formal reporting process, take steps to reduce further damage.
Use another phone or a trusted person's device to contact your bank.
Ask the bank to immediately secure your account and restrict compromised digital banking channels.
Contact your telecom provider to report the suspected unauthorised SIM replacement.
Secure your email and other important accounts, especially those that use the affected number for password recovery.
Preserve transaction alerts, messages, screenshots and any notifications related to the incident.
Do not share your PIN, password, OTP or verification codes with anyone claiming to be investigating the incident.
If money has already been transferred, report the unauthorised transactions to your bank immediately and request that it initiate the appropriate fraud investigation and recovery process.
The two reporting processes should happen simultaneously rather than waiting for one institution to finish before contacting the other.
Track One: How to Report SIM Swap Fraud to Your Bank
Your bank needs to know that your phone number may have been compromised because the fraudster could use it to access financial services or authorise transactions.
Do not assume that reporting the incident to your network provider automatically informs your bank.
Step 1: Contact Your Bank Through an Official Channel
Use your bank's official customer care number, mobile application, verified website or branch.
If your primary phone number is no longer working, contact the bank using another phone or visit a branch with valid identification.
Avoid calling numbers supplied by strangers or clicking links in unsolicited messages claiming to offer fraud assistance.
Step 2: Request Immediate Protection of Your Account
Explain that you suspect your registered phone number has been taken over through an unauthorised SIM swap.
Ask the bank to assess the risk and take appropriate protective action, which may include:
Temporarily restricting mobile and internet banking access.
Blocking compromised cards or payment channels where necessary.
Disabling or resetting affected authentication tokens.
Reviewing recent transactions and login activity.
Securing the phone number linked to your account.
Preventing further unauthorised transactions while the incident is investigated.
Ask the bank what restrictions are necessary to protect your funds without unnecessarily disrupting unaffected services.
Step 3: Report Every Unauthorised Transaction
If money has already left your account, provide the bank with the available details.
Include:
Date and approximate time of each transaction.
Amount involved.
Transaction reference or session ID, where available.
Recipient account details, if shown.
Any transaction alerts or bank notifications received.
The approximate time your SIM stopped working.
Ask the bank to initiate its fraud investigation and, where applicable, contact the receiving institution to request the appropriate recovery or transaction-tracing action.
Do not assume that a reversal is guaranteed. The outcome depends on the circumstances, available evidence and applicable banking procedures.
Step 4: Request a Formal Complaint Reference Number
After submitting your complaint, request a reference or ticket number.
This number is important because it helps you track the investigation and provides evidence that the incident was formally reported.
Ask the bank to confirm:
What security measures have been applied.
Which banking channels remain restricted.
Whether your registered phone number needs to be updated.
What additional documents are required.
When you should expect an update.
Step 5: Secure Your Banking Credentials
Once the bank has helped secure the affected channels, follow its instructions to reset compromised credentials.
Change passwords that may have been exposed, especially if they were reused across different services.
Where possible, use a separate, secure email address and authentication method that does not depend entirely on the compromised phone number.
Never give anyone your banking PIN, password, card security code or OTP, even if they claim to be bank staff.
READ MORE: How to Protect Your Phone From SIM-Based Tracking
Track Two: How to Report SIM Swap Fraud to Your Telecom Provider
Your telecom provider must investigate how your number was transferred and help restore your control of the line.
This is a separate complaint from the one submitted to your bank.
Step 1: Contact Your Network Provider Immediately
Contact your telecom operator through its official customer care channel or visit a customer service centre.
Nigeria's major mobile network operators include:
MTN Nigeria.
Airtel Nigeria.
Globacom (Glo).
9mobile.
If your SIM no longer works, use another phone or visit an authorised service centre.
Step 2: Report an Unauthorised SIM Replacement
Clearly explain that your phone number may have been transferred to another SIM without your permission.
Ask the operator to:
Investigate the suspected SIM swap.
Check whether a SIM replacement or account change was processed.
Secure the affected mobile number.
Suspend or reverse an unauthorised replacement where appropriate.
Restore the number to your control after identity verification.
Check for suspicious changes to your subscriber records.
The NCC has specifically stated that it addresses fraudulent SIM swaps by engaging operators and ensuring that a number is re-registered to the complainant where an unauthorised swap is established.
Step 3: Request a Complaint Reference Number
Do not end the conversation without requesting a complaint or ticket number.
Keep this reference because you may need it when escalating the matter to the NCC.
Also ask the provider to confirm the complaint in writing, where possible.
Step 4: Verify Your Identity and Restore Your Number
The telecom provider may require you to complete an identity verification process before restoring the number.
You may be asked to provide relevant subscriber information and identification documents.
Follow the operator's official instructions, and avoid sending sensitive documents to unofficial phone numbers or social media accounts.
Step 5: Secure Your SIM Account
After your number has been restored, ask the provider whether it offers additional account security measures.
These may include:
A special account password or security PIN.
Additional verification for SIM replacement requests.
Alerts for SIM changes.
Restrictions on certain account modifications.
The available options differ between operators.
Why Reporting to Both Your Bank and Telco Matters
A SIM swap incident can involve two separate systems: telecommunications and financial services.
Reporting to only one institution may leave the other part of the incident unresolved.
| What needs protection? | Who should you contact? | What should they investigate? |
|---|---|---|
| Your mobile number | Telecom provider | Unauthorised SIM replacement and restoration of your line |
| Your bank account | Bank | Unauthorised transactions, access attempts and account security |
| Other digital accounts | Relevant service providers | Password resets, suspicious logins and account recovery |
| Unresolved telecom complaint | NCC | The telecom operator's handling of your complaint |
| Unresolved banking complaint | CBN | The bank's handling of your complaint |
| Suspected criminal activity | Nigerian Police / National Cybercrime Centre | Fraud, identity theft and related criminal activity |
The bank and telecom provider may need to coordinate, but you should not rely on them to automatically share every detail of your complaint.
Keep separate records of both reports.
READ MORE: How to Freeze a Stolen SIM Remotely Before It Is Used for Fraud
What Evidence Should You Keep?
Evidence can help the institutions investigate the incident and understand how the fraud occurred.
Keep copies of:
Screenshots of transaction alerts.
Bank statements showing suspicious transactions.
SMS messages about SIM replacement or account changes.
Screenshots of unusual password-reset notifications.
Your telecom complaint reference number.
Your bank complaint reference number.
Dates and times when your SIM stopped working.
Names or identifiers of customer service representatives, where available.
Any written responses from the bank or telecom provider.
Do not delete suspicious messages or notifications before documenting them.
If you have already reported the incident, keep a record of every follow-up conversation and any instructions given by the institutions.
Where to Escalate If Your Bank or Telco Does Not Respond
Reporting the incident is only the first step. If either institution fails to address the complaint, there are regulatory and law-enforcement channels available.
1. Escalating a Telecom Complaint to the NCC
If your telecom provider does not resolve the issue satisfactorily, you can escalate the complaint to the Nigerian Communications Commission.
The NCC advises consumers to contact their service provider first, obtain a complaint reference number and escalate unresolved complaints through its consumer channels.
When escalating, include your telecom provider's complaint reference, a description of the suspected SIM swap and the steps already taken.
2. Escalating a Banking Complaint to the CBN
If your bank does not resolve your complaint within the applicable period, you can escalate the matter to the Central Bank of Nigeria's Consumer Protection Department.
The CBN's published complaint procedure directs customers to complain to their financial institution first. Its guidance states that customers may escalate unresolved complaints after two weeks, subject to the applicable complaint category and timeline.
Include evidence that you first lodged the complaint with your bank, together with the relevant transaction details and supporting documents.
Do not include your banking PIN or password in a complaint letter.
3. Reporting the Incident to the Police
SIM swap fraud involving unauthorised access, identity theft or stolen funds may constitute criminal activity.
A Sample Message to Send to Your Bank
If you are unsure how to explain the incident, you can adapt this message:
Subject: Urgent Complaint – Suspected SIM Swap Fraud and Account Security
Dear Customer Support Team,
I am writing to report a suspected SIM swap fraud involving the mobile number registered to my bank account.
My phone number has unexpectedly lost network service, and I suspect that an unauthorised SIM replacement may have occurred.
I am concerned that my banking information and transaction authentication may have been compromised.
Please immediately investigate the incident, secure my account, restrict any potentially compromised banking channels and review any suspicious transactions or access attempts.
Kindly provide a complaint reference number and advise me on the next steps required to protect my account.
Thank you.
A Sample Message to Send to Your Telecom Provider
Subject: Urgent Report of Unauthorised SIM Swap
Dear Customer Support Team,
I wish to report a suspected unauthorised SIM swap involving my mobile number.
My original SIM card has unexpectedly lost network service, and I am concerned that my number may have been transferred to another SIM without my consent.
Please investigate any recent SIM replacement or account changes associated with my number, secure the line against further unauthorised access and assist me with restoring control of my number after the necessary verification.
Kindly provide a complaint reference number and confirm the steps being taken to resolve the issue.
Thank you.
READ MORE: What Is eSIM, and Is It Available in Nigeria Yet?
How to Prevent SIM Swap Fraud in the Future
Although no security measure can eliminate every risk, a few precautions can make it harder for criminals to take control of your number.
Protect your personal information: Avoid sharing your NIN details, date of birth and other identity information unnecessarily. Criminals may use personal information to impersonate subscribers.
Be cautious with unexpected verification requests: Never share OTPs, banking PINs or passwords with anyone who contacts you.
Secure your email account: Your email may be used to reset passwords on financial and digital services. Use a strong, unique password and additional authentication where available.
Ask your network provider about SIM replacement security: Find out whether additional verification or an account security PIN can be enabled.
Monitor your banking activity: Review transaction notifications and statements regularly so that unusual activity is identified quickly.
Use multiple security measures: Where available, use authenticator applications, passkeys or other secure authentication methods instead of relying exclusively on SMS verification.
Keep your contact information updated: Ensure your bank and other important service providers have accurate contact details.
Conclusion
SIM swap fraud is not just a telecommunications problem. It can quickly become a financial security problem when criminals use a compromised phone number to access banking services and other digital accounts.
That is why victims should report the incident to both their bank and telecom provider immediately.
The bank needs to secure the financial account and investigate suspicious transactions, while the telecom operator must investigate the unauthorised SIM replacement and help restore the affected number.
Keep evidence, request complaint reference numbers and escalate unresolved issues to the appropriate regulator.
Most importantly, do not wait for money to disappear before acting. If your SIM suddenly stops working and you suspect an unauthorised replacement, treat it as a potential security incident and report it immediately.