If your phone or SIM card is stolen, don't wait until you notice a suspicious bank transaction before taking action.

Your SIM may be connected to your bank accounts, email accounts, WhatsApp, social media and other services that use your phone number for verification.

The Nigerian Communications Commission (NCC) advises consumers to contact their network provider immediately after a SIM or phone is lost or stolen and request that the SIM be blocked.

Here's what to do.

1. Block the SIM immediately

Contact your mobile network operator through an official customer-care channel and report the SIM as stolen.

Tell them clearly:

"My SIM has been stolen. I want the line blocked immediately."

The operator will usually need to verify that you are the legitimate subscriber.

For example, MTN currently allows customers to block a stolen line through *123*7*4# or *123*7# and selecting the relevant option. MTN also says customers can contact its support team and answer security questions before the line is blocked.

If you use another network, use its official customer-care channel rather than a random number found online.

2. If your phone was also stolen, lock it remotely

Blocking the SIM protects the number, but it doesn't protect the physical phone itself.

If you have an Android phone, use Google's Find Hub to remotely lock or erase the device where available.

For an iPhone, use Apple's Find My service to mark the device as lost and protect it.

Do this as soon as possible, especially if the phone was unlocked when it was stolen.

3. Contact your bank immediately

This step is extremely important.

If your stolen SIM was linked to your bank account, contact your bank and explain that your phone/SIM has been stolen.

Ask the bank to review the security of services linked to the number and place appropriate restrictions where necessary.

MTN specifically advises customers whose SIMs are lost or stolen to notify their financial institutions so mobile-banking services associated with the SIM can be suspended or account restrictions placed where appropriate.

Don't wait for money to disappear before contacting your bank.

4. Secure your email account

Your email may be another route into your other accounts.

From another device:

  • Change your email password.

  • Sign out unfamiliar devices.

  • Check recent login activity.

  • Confirm your recovery email and phone number.

  • Enable two-factor authentication.

  • Replace the stolen phone number as a recovery method where possible.

Pay particular attention if your email uses the stolen number for password recovery.

5. Secure WhatsApp and social-media accounts

If WhatsApp was active on the stolen phone, secure your account as soon as possible.

You should also check your Facebook, Instagram, X, Google and other important accounts for unfamiliar login sessions.

Never give anyone a verification code because they claim they are helping you recover the stolen number.

6. Get a replacement SIM with the same number

Blocking the old SIM does not necessarily mean you have lost your phone number permanently.

You can request a SIM replacement/SIM swap from your network provider, subject to its verification requirements.

For example, MTN says a stolen or lost SIM can be replaced while retaining the existing phone number, provided the subscriber meets its verification requirements.

The NCC also has a SIM replacement policy for subscribers whose SIMs are lost, stolen or damaged, subject to NIN verification and applicable requirements.

7. Don't confuse SIM locking with remotely blocking a stolen SIM

A SIM PIN is useful protection, but it is not the same thing as remotely blocking a stolen SIM.

A SIM PIN can prevent someone from using the SIM in another phone without the PIN, if it was already enabled.

But once the SIM is physically stolen, you should still contact the network operator and request a block.

The NCC recommends using a SIM PIN and also contacting the network operator immediately if the SIM or phone is lost or stolen.

8. Watch your bank and other accounts

For the next few days, pay close attention to:

  • Bank transactions

  • OTP messages

  • Password-reset notifications

  • New-device login alerts

  • WhatsApp activity

  • Email security alerts

  • Mobile-money transactions

  • Unusual calls or messages from your contacts

If you see an unauthorized transaction, contact your bank immediately and report it as fraud.

What if your network provider doesn't block the SIM?

Start with the network provider and keep the complaint/ticket number.

The NCC's current complaint procedure says consumers should first complain to their service provider, obtain a complaint or ticket number, and allow the provider's stated resolution period to pass. If the issue remains unresolved, the complaint can be escalated to the NCC.

The NCC can be reached through 622, its Consumer Portal and other official channels.

The emergency order to remember

If your phone or SIM is stolen:

BLOCK SIM → CONTACT BANK → LOCK PHONE → SECURE EMAIL → SECURE SOCIAL ACCOUNTS → REPLACE SIM → MONITOR ACCOUNTS

The most important part is speed.

Don't wait for a fraudulent transaction before treating a stolen SIM as a security emergency.