Yes, someone can stop your SIM card through a scam called a "SIM swap," where they trick your mobile provider into transferring your number to their SIM, giving them access to your texts and calls, especially 2FA codes. To prevent this, you need to contact your carrier immediately to report a lost/stolen SIM, use strong passcodes, enable authenticator apps, and secure accounts with unique, complex passwords.
If the hackers get enough of your personal details correct, your cell phone service provider will issue them a new SIM card and deactivate the old one. Once the scammers acquire the new SIM card, they can intercept all calls and messages, including any Two-Factor or Multi-Factor authentication texts.
Common causes of a blocked SIM card
A SIM card can become blocked for several reasons: ❌ Incorrect PIN entered too many times → requires the PUK code to unlock. ❌ Network lock on the device → the phone only works with a specific carrier. ❌ Compatibility issues → different network bands, technologies, or regions.
Contact your mobile operator: Immediately inform our support team about the loss or theft of your SIM card. Be ready to answer security questions that validate your ownership of the SIM, and we will block the SIM card instantly to prevent unauthorized use.
How to know if someone has blocked your number
If you enter your PIN (Personal Identification Number) code incorrectly several times, the SIM card is locked. You then need the PUK (Personal Unblocking Key) code to unlock the device. The PIN and PUK codes are used to protect your subscription and device against unauthorised use.
You can tell if someone blocked your number if your calls go straight to voicemail (after one ring), texts show as undelivered (like on WhatsApp), or you're blocked on social media; however, the surest way is to call from another phone: if your calls don't go through from your number but do from another, you're likely blocked, though consistent patterns over time are key to differentiate from normal DND/airplane mode.
Here are some common issues you can look into before you troubleshoot:
Once you block your Airtel SIM card using any of the above methods, here's what you can expect: All outgoing and incoming services on your number will be suspended immediately. You will not be able to make or receive any calls, SMS, or data. Your SIM will be permanently deactivated within 24-48 hours.
If you enter the PIN (Personal Identification Number) code incorrectly several times, the SIM card will be locked. You need the PUK (Personal Unblocking Key) code to unlock the device.
Airtel: Dial *121# and input your eleven-digit NIN number. A confirmation message will be sent indicating that the SIM card has been successfully unbarred. 9Mobile: Dial *200*8#. Glo: Dial *109* Your NIN number#.
Check for any visible signs of damage, like scratches or stains. Clean the SIM card and tray with a clean, dry cloth. Reinsert the SIM card, making sure to properly align the card with the tray. Once the SIM card tray is secured in place, turn your phone on to see if the error has been resolved.
Signs Your SIM May Be Compromised
Dial codes like *#21# or *#62# help check call forwarding settings, but they can't confirm if your phone is hacked. They're useful for spotting suspicious redirections, but use trusted antivirus apps for reliable threat detection.
Can You Tell If Your Phone Has Been Hacked? Unfamiliar apps, losing access to your accounts, call and messaging features that suddenly stop working, and performance issues — such as apps crashing, a hot or loud device, and reduced battery life — are all common signs that your phone has been hacked.
A locked SIM makes it significantly harder for hackers. Protects Lost or Stolen Devices: Even if someone gets hold of your phone, they can't use your mobile network or identity. Safeguards 2FA and Banking Apps: Many accounts rely on SMS codes for verification. A locked SIM ensures those codes stay safe.
Android Device
Tap on Mobile Data. Locate SIM PIN and tap it. Toggle the SIM PIN to ON. Input your current SIM PIN if the SIM wasn't locked use the default pin below Click on Change PIN Input the default PIN again Enter a new SIM PIN to lock your SIM card Press Done Make sure that you remember it!
Lock your SIM card or eSIM with a PIN (personal identification number) to require an identification code for phone calls and cellular-data usage. To protect your SIM card or eSIM from others using it for phone calls or cellular data, you can use a SIM PIN.
Be sure you're using the SIM that came with your device or one verified to be compatible. Exposure to moisture causing corrosion or electrical problems. Physical damage to the SIM card (e.g., bending/breaking, scratched or corroded contacts, debris inside the device's SIM card slot, etc.).
Typically, SIM cards last 5-10 years with normal use. However, physical damage or environmental factors can shorten their lifespan and stop working early.
This star code will unblock your caller ID for a single outgoing call if you have previously used *61 to block caller ID for all outbound calls.
When you text someone who blocked you, the message generally sends from your end but is blocked from reaching the recipient; you typically won't get an error message, but you won't see a "Delivered" notification (on iPhones, it might stay blue but lack delivery confirmation, while on Android, it might show "Not Delivered" or just hang, but you can't know for sure without them telling you or trying other methods like calls to voicemail or different apps).
Signs you may have been blocked
If you have an iPhone and text another iPhone but don't see a “Delivered” notification, someone may have blocked you. (Android phones don't automatically show these messages.) The same goes for if you consistently see a green text bubble instead of a blue one on your iPhone.