SECURITY
SIM Swap Warning Signs and Immediate Actions
Recognise sudden loss of service, protect carrier accounts and secure online accounts after a suspected SIM swap.
A SIM swap occurs when a phone number is moved to another SIM or eSIM without the owner’s permission. The attacker may then receive calls and SMS codes. Fast action matters because the number may be connected to email, financial and social accounts.
Warning signs
Unexpected loss of mobile signal, a carrier message about a SIM change, inability to make calls and new login alerts can indicate a swap. A local outage or damaged SIM can look similar, so verify with the carrier from another trusted phone. Do not wait for service to return if sensitive accounts use SMS recovery.
Contact the carrier
Use the carrier’s official published number or visit an authorised store with identification. Ask whether a SIM or eSIM change occurred, suspend unauthorised service and secure the account with a PIN. Request records or a complaint reference where available.
Secure online accounts
From a trusted internet connection, change the primary email password first, then financial and other important accounts. Revoke unknown sessions, remove unfamiliar recovery details and replace SMS with a passkey, security key or authenticator where possible. Notify financial providers about the suspected compromise.
Prevent the next attempt
Set a carrier PIN or port-out lock if supported, minimise the personal details available publicly and avoid using the phone number as the only recovery factor. Keep recovery codes offline and add security alerts. Review carrier and account settings after every legitimate SIM replacement.
Quick checklist
- Verify loss of service with carrier
- Suspend unauthorised SIM activity
- Secure primary email first
- Review financial accounts
- Replace SMS-only recovery
Frequently asked questions
Can a SIM swap happen while I still have my phone?
Yes. It targets control of the number, not necessarily the physical handset.
Will changing the phone password stop it?
No. Secure the carrier account and online accounts separately.