# SIM Swap Fraud and SMS Codes | ZafeConnect

> What SIM swap fraud is, why it threatens SMS one-time codes, the warning signs, and the controls a business can add without giving up SMS.

Canonical URL: https://www.zafeconnect.com/blog/sim-swap-fraud-and-sms-codes
Language: en
Last modified: 2026-11-09

## SIM swap fraud: what it is and how to reduce the risk

URL: https://www.zafeconnect.com/blog/sim-swap-fraud-and-sms-codes

Published: 2026-11-09

If an attacker moves a victim’s phone number to a SIM card they control, they also receive the victim’s text messages, including the codes that protect accounts.

Key takeaways:
- In a SIM swap, a criminal has the victim’s number transferred to another SIM and then receives the victim’s calls and texts.
- The attack targets the phone number, not the SMS message itself.
- Controls belong in your sign-in and account-change flows: step-up checks, delays and notifications through another channel.
- A messaging provider delivers the message; it cannot stop someone who controls the number.

### How the attack works
The attacker collects personal details about the victim and then persuades the operator, or an employee, to move the number to a new SIM card. From that moment the victim’s phone loses service and the attacker receives the texts.

The attacker then starts a password reset or a sign-in on a target service and uses the code that arrives on the new SIM. The weakness is not in SMS as a message format but in how easily a number can be moved.

### Warning signs

- A customer reports that their phone suddenly lost service
- A password reset or new-device sign-in is followed at once by changes to contact details or payees
- The phone number was recently ported or changed
- Sign-ins from a new device and a new location right after a code request

### Controls you can add

- Ask for a stronger factor before high-value actions, such as an authenticator app or a passkey
- Delay or add friction to sensitive changes soon after a code-based recovery, for example adding a payee or changing the phone number
- Notify the customer by another channel, such as email or an app, when a number or security setting changes
- Where your countries and partners offer a signal that a number was recently swapped or ported, use it as an input to risk decisions
- Do not let SMS alone unlock the most valuable actions

### What to tell your customers

- Ask the operator about a PIN or extra protection on the account
- Be careful with personal details shared publicly
- Contact the operator at once if a phone loses service without explanation
- Check any message about a changed number or security setting, and report ones that were not requested

### How ZafeConnect fits
ZafeConnect delivers one-time codes and other A2P messages to 190+ countries and offers Numbers Lookup and SenderID Protection as separate products. SIM-swap detection is a control in your own flows; talk to us about what signals are available in the countries you serve.

FAQ:
Q: Is SIM swap the same as SMS interception?
A: No. In SIM swap the attacker legitimately receives the messages because the number now belongs to their SIM. Interception means reading messages in transit, which is a different attack.

Q: Can an SMS provider prevent SIM swap fraud?
A: A provider delivers the message to the number it is given. Prevention sits with the operator and with your own sign-in and account-change flows.

Q: Should I stop using SMS codes?
A: Not necessarily. Use them for reach, and add stronger methods and checks for high-value actions.