SIM Binding

SIM binding lets you tell whether the SIM currently in the device is the same one that was used during the last successful authentication. Use it to gate sensitive actions (payments, profile changes) or to force re-auth after a SIM swap. Available from otpless-headless-sdk v2.1.0. The feature is opt-in and disabled by default.

How it works

After a successful Silent Network Authentication (SNA) or SMS OTP auto-read, the SDK records a fingerprint and stores it into encrypted storage. checkSimBindingStatus() compares that fingerprint against the current SIM and returns true only when they match. The binding is written and cleared automatically:

Outcome	Effect
Successful ONETAP where the identity is marked SIM-bound	Binding saved
Successful ONETAP where the identity is not marked SIM-bound	Any existing binding cleared
SIM slot cannot be resolved, or an exception occurs while saving	Any existing binding cleared
Encrypted storage unavailable on the device	No-op (all APIs return `false`)

Enable SIM binding

Set the toggle once, before starting authentication:

import com.otpless.v2.android.sdk.main.OtplessSDK

OtplessSDK.isSimBindingEnabled = true

Check binding status

checkSimBindingStatus can be called without first calling OtplessSDK.initialize — pass an application Context directly.

lifecycleScope.launch(Dispatchers.IO) {
    val isSameSim = OtplessSDK.checkSimBindingStatus(applicationContext)
    if (isSameSim) {
        // SIM matches the one used at last successful auth — proceed.
    } else {
        // No binding, SIM swapped, device changed, or storage unavailable — re-authenticate.
    }
}

Returns true only when a binding is stored and the current SIM matches it. Any exception is swallowed and the call returns false.

Clear the binding

Call after logout, account deletion, or whenever the user should be forced through a full auth again. Also callable without initialize.

lifecycleScope.launch(Dispatchers.IO) {
    OtplessSDK.clearSimBinding(applicationContext)
}

API summary

Member	Type	Notes
`OtplessSDK.isSimBindingEnabled`	`var Boolean`	Default `false`. Must be `true` for the SDK to save bindings.
`OtplessSDK.checkSimBindingStatus(context)`	`suspend`	Returns `Boolean`. Callable without `initialize`.
`OtplessSDK.clearSimBinding(context)`	`suspend`	Deletes the stored binding. Callable without `initialize`.

Get Started

Native/Mobile SDKs

Web SDKs

References

How it works

Enable SIM binding

Check binding status

Clear the binding

API summary

​How it works

​Enable SIM binding

​Check binding status

​Clear the binding

​API summary

How it works

Enable SIM binding

Check binding status

Clear the binding

API summary