Scammers often impersonate others to get replacement SIM cards and receive their SMS verification codes. SIM Swap lets a bank ask the operator before a transfer: Has the SIM card for this phone number changed recently?
The same SIM card has always been used, with no SIM change recorded within the query window.
The SIM card changed six months ago, outside the query window. Looking up the most recent SIM change returns April 2.
The SIM card changed yesterday, within the query window, so the response is “SIM changed.”
A and BBoth return “no SIM change.” To get the exact date, look up the most recent SIM change instead.
CThe SIM card changed within the last 240 hours, so the bank can add an extra check before a transfer.
SIM Swap: How it works
- SIM change recordsWhenever a SIM card is reissued or replaced, the operator records the change in the link between the phone number and SIM card.
- Specify the windowThe service provider sends the phone number and specifies how many recent hours to check. The default is 240 hours.
- ResponseThe operator returns whether the SIM card changed within the window, or the time of the most recent SIM change.
SIM Swap: API spec
POST /check checks for a SIM change within the window; POST /retrieve-date retrieves the time of the most recent SIM changephoneNumber; query window maxAge (hours, 1–2400, default 240)| Response fields | Meaning | Example |
|---|---|---|
| swapped | Whether the SIM card changed within the query window | true |
| latestSimChange | Time of the most recent SIM change | 2026-10-12T08:30:00Z |
| monitoredPeriod | The number of days the operator has monitored; may be included if the most recent SIM change predates this period | 120 |
Responses for three scenarios (excerpts)
falseNo SIM change in the last 240 hoursfalseNo SIM change in the last 240 hours (/check response)2026-04-02Date of the most recent SIM change (/retrieve-date response)trueSIM changed in the last 240 hours (/check response)2026-10-12Date of the most recent SIM change (/retrieve-date response)Spec source: CAMARA SimSwap r3.3 (SIM Swap v2.1.0)
SIM Swap: GSMA use cases
Fraud Detection in Mobile Insurance Claims
Problem to solveFraudulent claims for lost or stolen phones are increasing. Manual checks are slow and prone to errors.
SIM Swap's roleDetects recent SIM card changes, which can provide supporting evidence for a claim.
Used together: Device Swap, Device Identifier
GSMA source ↗Vehicle Recycling Centre
Problem to solveAfter a vehicle is scrapped, its eSIM often remains active, creating risks of data leaks, unauthorized access, and regulatory violations.
SIM Swap's roleDetects recent SIM card changes to prevent misuse during vehicle scrapping.
Used together: Number Recycling, Location Retrieval
GSMA source ↗Reducing fraudulent online ticket purchases
Problem to solveOnline ticket sales for popular events often face fraudulent purchases, affecting fairness and the buying experience.
SIM Swap's roleDetects recent SIM card changes to reduce the risk of impersonation.
Used together: Number Verification
GSMA source ↗Connected and Validated delivery services
Problem to solveDeliveries of high-value or regulated items require identity checks for couriers and recipients, along with real-time tracking.
SIM Swap's roleDetects recent SIM card changes to prevent impersonation.
Used together: Number Verification, Location Verification, Quality on Demand
GSMA source ↗Account Takeover Protection
Problem to solveBanks detect fraud during mobile authentication to prevent account takeover.
SIM Swap's roleChecks whether the SIM card has changed recently.
Used together: Call Forwarding Signal
GSMA source ↗GSMA case studies (5)
Sources: GSMA Open Gateway Use Case Library and API Descriptions (accessed 2026-10-14). Descriptions are summaries.