SIM swap fraud: my phone suddenly has no signal, what do I do?

SIM swap fraud: my phone suddenly has no signal, what do I do?

You look at your phone and it says "No service" or "SOS only". You're at home, where you always have signal, and the people around you on the same network are fine. You can't call or receive texts. It might be a fault, but it might also be SIM swap fraud: someone has convinced your mobile network to move your number onto a new SIM card in their hands. From that moment, the texts with your bank's security codes go to them. If this is happening to you, act now: every minute counts.

How does a SIM swap work?

1. They gather your details. Name, date of birth, address, sometimes your account number or the answers to security questions. They get them from data breaches, phishing texts, fake calls or social media.
2. They impersonate you to your network. By phone, online or in a shop, they claim to be you and say they've lost their phone or need a new SIM or eSIM. If they convince the network, your number is moved to their card.
3. Your SIM stops working. Your phone loses service because your number now lives on another SIM.
4. They use your number to get into your accounts. They request password resets and one-time codes by text: online banking, email, WhatsApp, payment apps. With those codes they can move money or set up new payees.

Often the first sign comes before you lose signal: a suspicious text or call asking for "security details", or a message from your network about a SIM change you didn't request.

What are the warning signs?

• No service or "SOS only" with no explanation, while others on your network are fine.
• A message from your network about a SIM or eSIM change, a new device or a number transfer that you didn't ask for.
• Emails about password changes or new logins to your accounts.
• Bank alerts about new payees, new devices or payments you don't recognise.
• Contacts telling you they've received strange messages from your number.

What do I do right now?

1. Restart your phone to rule out a simple fault. If there's still no service and others on your network have signal, assume it's fraud.
2. Contact your mobile network from another phone (a family member's, a landline, or the network's live chat on another device). Use the customer service number from its official website. Say you suspect SIM swap fraud, ask them to block the line and confirm whether a new SIM or eSIM has been issued.
3. Call your bank straight away. Dial 159 to be connected securely to many UK banks, or use the number on the back of your card. Ask them to block online banking and cards and check for new payees, devices or payments.
4. Change your email password from a safe device, because email is the gateway to resetting everything else. Then change your banking and other important passwords. The NCSC explains how to recover a hacked account.
5. Sign out of all sessions on your email and social media accounts, and check the security settings for changes you didn't make.
6. Warn your contacts that messages from your number may not be from you.

What if money has already been taken?

1. Tell your bank in detail what has happened, including that your SIM was swapped without your permission.
2. Ask for the payments to be investigated. Payments you didn't authorise should, as a rule, be refunded by your bank, unless it can show you acted fraudulently or with gross negligence.
3. Report it to Report Fraud (formerly Action Fraud) on 0300 123 2040 in England, Wales and Northern Ireland, or to Police Scotland on 101. Bring the timeline: when you lost service, when you called your network and the bank, and which payments you don't recognise.
4. Make a complaint to your mobile network about the unauthorised SIM change and ask them for the details of when and how it was done.
5. If the bank or the network rejects your complaint, you can take it further. For banking issues, the Financial Ombudsman Service is free; for complaints about your phone provider, ask it which ombudsman or dispute resolution scheme it belongs to.
6. Consider protective registration with Cifas to make it harder for criminals to use your identity, and check your credit file for applications you didn't make.

How do I stop it happening again?

• Ask your network about extra security, such as a password or PIN required for any SIM change.
• Don't share personal details with anyone who calls or texts you, even if they claim to be your bank or network.
• Use an authenticator app or passkeys rather than text codes wherever you can. The NCSC explains how to turn on two-step verification.
• Set a SIM PIN on your phone, so a stolen card can't be used in another handset.
• Turn on notifications in your banking app so you know instantly about any new payee or payment.
• Limit what you share on social media: your date of birth, address and family names are useful to fraudsters.

Frequently asked questions

Could it just be an outage? Yes. Check your network's status page from another device or ask someone on the same network nearby. If there's an outage, everyone is affected; if it's only you, call your network.

Will I get my number back? Normally, yes. Once your network confirms the fraud, it can issue you a new SIM or eSIM with your number and cancel the fraudster's.

I have an eSIM. Can this happen to me too? Yes. The fraud isn't about the physical card: it's about convincing the network to move your number to a device the criminal controls.

What about WhatsApp? If they have your number, they can try to register your WhatsApp on their phone. When you get your line back, register it again and turn on two-step verification in WhatsApp.

In short

If your phone suddenly loses service for no reason, don't wait: call your network from another phone, call your bank on 159, change your email password and warn your contacts. Then report it and keep a record of everything. And if you've received suspicious calls or texts beforehand, report the number in the NoCall spam numbers directory: your warning could protect someone else.