SIM Change Detection — Android Background Service

Continuously monitor SIM state changes to help mitigate SIM-swap account takeovers. Runs silently in the background and sends only non-sensitive metadata for risk scoring. 

 High-level flow 

 

 

 User installs/opens the banking app with the SDK. 

 

 

 A lightweight background service starts automatically (and after reboots). 

 

 

 Service periodically checks SIM state allowed by Android. 

 

 

 If the current SIM differs from the baseline, an event is triggered. 

 

 Event (NO_CHANGE | SIM_CHANGED | UNKNOWN) + session metadata is sent securely to the backend. 

   

 

 

 Required permission (AndroidManifest.xml) 

 <uses-permission android:name="android.permission.READ_PHONE_STATE"/>

 

 Notes: Android 10+ restricts some identifiers; behavior varies by OEM. 

 Event types 

 

 

 NO_CHANGE — SIM unchanged 

 

 

 SIM_CHANGED — SIM differs from baseline 

 

 

 UNKNOWN — SIM info unavailable on device/OS 

 

 

 Example payload to backend 

 {

 "device_id": "abcd-1234",

 "timestamp": "2025-09-16T15:00:00Z",

 "sim_status": "SIM_CHANGED",

 "carrier": "CarrierName",

 "os_version": "Android 14",

 "sdk_version": "2.1.0"

}

 

 Security & privacy 

 

 

 No SMS/contacts/phone numbers are read; only SIM status + technical metadata. 

 

 TLS 1.2+ for transport; designed for data minimization. 

 

 Limitations & compatibility 

 

 

 Android-only; newer Android versions/OEMs may mask info. 

 

 

 Dual-SIM devices may complicate detection; not available on iOS. 

 

 Maintain a tested device/OS compatibility list and validate before rollout. 

 

 Next steps 

 

 

 Add permission. 

 

 

 2) Initialize background service at app start. 

 

 

 3) Ingest events server-side. 

 

 

 4) Combine with other signals for scoring. 

 

 

 5) Validate on your device matrix pre-production.