> ## Documentation Index
> Fetch the complete documentation index at: https://otpless.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Integrate Native Truecaller SDK

> Step-by-step guide to enable Truecaller SSO with Otpless Headless SDK.

This section provides a detailed walkthrough on how to integrate the **Truecaller SDK** with the **Otpless Headless SDK**.

## Step 1: Prerequisites

1. Before you proceed with integrating Truecaller SDK, make sure to complete the integration steps from the [OTPless Android Headless SDK Documentation](/docs/frontend-sdks/app-sdks/android/new/headless/intro).
2. Make sure you have ask OTPless support to enable Truecaller SSO

## Step 2: Add Dependency

**Add the required SDK dependencies**

```groovy Build.gradle theme={null}
dependencies {
    implementation ("io.github.otpless-tech:otpless-truecaller-sdk-impl:latest_version")
}
```

<Note>
  Use the latest version of - [Otpless Truecaller SDK](https://central.sonatype.com/artifact/io.github.otpless-tech/otpless-truecaller-sdk-impl)
</Note>

## Step 3: Create Truecaller App and Update Client Id

* Register your app on the [Truecaller Developer Console](https://developer.truecaller.com).
* Copy the below line of code in your string.xml.
* Replace TRUECALLER\_CLIENT\_ID with the client id provided by truecaller on dashboard.

```xml theme={null}
<string name="otpless_truecaller_client_id">TRUECALLER_CLIENT_ID</string>
```

<Note>
  During development, make sure to also register your test phone numbers and **SHA-256 fingerprints** in the same section to avoid authentication failures.
</Note>

## Step 4: Create Truecaller request

* All Parameters are optional and has a equivalent map with the parameters of Truecaller SDK

```kotlin Kotlin theme={null}
val trueCallerRequest = OtplessTruecallerRequest(
    heading = OTHeadingConsent.SDK_CONSENT_HEADING_LOG_IN_TO
)
```

### Parameters

* **footerType** → Type of footer (e.g., disclaimer or consent note).
* **shape** → Button shape (rectangle, rounded, circular).
* **verifyOption** → Verification method (auto/manual/server-side).
* **heading** → Heading or consent text above the button.
* **loginPrefixText** → Prefix text before the login button (e.g., *Login with*).
* **ctaText** → Call-to-action text inside the button.
* **locale** → Language/region setting for UI texts.
* **buttonColor** → Background color of the login button.
* **buttonTextColor** → Text color of the login button.

## Step 5: Initialize the Truecaller SDK

* Initialize the Truecaller SDK inside your `Activity` or `Fragment`. This step ensures that the SDK is properly set up to handle authentication flows via Truecaller.
* You should call `initTrueCaller` after calling `OtplessSDK.init` in activity or `onViewCreated` method of fragment.
* `initTrueCaller` returns `boolean` which tells if truecaller authentication is supported or not.
* If truecaller authentication is not supported then you should continue with smart authentication.

```kotlin Kotlin theme={null}
// initialize the truecaller
val initResult = OtplessSDK.initTrueCaller(requireContext(), trueCallerRequest) {
    // provide the scope
    OTScopeRequest.FragmentRequest(fragment, listOf(OTScope.OPEN_ID, OTScope.PHONE, OTScope.PROFILE))
    // OTScopeRequest.ActivityRequest(activity , listOf(OTScope.OPEN_ID, OTScope.PHONE, OTScope.PROFILE))
}
// If initResult is true you can proceed to trigger Truecaller request via OTPless SDK
```

## Step 6: Handle `onActivityResult`

Depending on your integration type, override the `onActivityResult` method in the correct component:

* **Fragment** → if you used `OTScopeRequest.FragmentRequest`
* **Activity** → if you used `OTScopeRequest.ActivityRequest`

```kotlin Kotlin theme={null}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    OtplessSDK.onActivityResult(requestCode, resultCode, data)
}
```

## Step 7: Start the Truecaller SSO Flow

* To start the sign-in process with Truecaller, create an **Otpless request** and set the channel type to `TRUECALLER`.
* Invoke the SDK using `OtplessSDK.start`.

```kotlin Kotlin theme={null}
if (initResult) {
    lifecycleScope.launch {
        val request = OtplessRequest()
        request.setChannelType(OtplessChannelType.TRUECALLER)
        OtplessSDK.start(request, this::onOtplessResponse)
    }
}
```

# Truecaller Native Authentication Flow

<img src="https://mintcdn.com/otpless-96/fXjR8HVPacjfZv4o/images/truecaller_authentication_flow.png?fit=max&auto=format&n=fXjR8HVPacjfZv4o&q=85&s=85095d0881a6711cd7b7b2708a842dbd" width="3840" height="3690" data-path="images/truecaller_authentication_flow.png" />