Telnyx WebRTC – Android SDK

Build real-time voice communication into Android applications using Telnyx WebRTC.

Prerequisites: Create WebRTC credentials and generate a login token using the Telnyx server-side SDK. See the telnyx-webrtc-* skill in your server language plugin (e.g., telnyx-python, telnyx-javascript).

Installation

Add JitPack repository to your project’s build.gradle:

allprojects {
    repositories {
        maven { url 'https://jitpack.io' }
    }
}

Add the dependency:

dependencies {
    implementation 'com.github.team-telnyx:telnyx-webrtc-android:latest-version'
}

Required Permissions

Add to AndroidManifest.xml:

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<!-- For push notifications (Android 14+) -->
<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
<uses-permission android:name="android.permission.FOREGROUND_SERVICE_PHONE_CALL"/>

Authentication

Option 1: Credential-Based Login

val telnyxClient = TelnyxClient(context)
telnyxClient.connect()

val credentialConfig = CredentialConfig(
    sipUser = "your_sip_username",
    sipPassword = "your_sip_password",
    sipCallerIDName = "Display Name",
    sipCallerIDNumber = "+15551234567",
    fcmToken = fcmToken,  // Optional: for push notifications
    logLevel = LogLevel.DEBUG,
    autoReconnect = true
)

telnyxClient.credentialLogin(credentialConfig)

Option 2: Token-Based Login (JWT)

val tokenConfig = TokenConfig(
    sipToken = "your_jwt_token",
    sipCallerIDName = "Display Name",
    sipCallerIDNumber = "+15551234567",
    fcmToken = fcmToken,
    logLevel = LogLevel.DEBUG,
    autoReconnect = true
)

telnyxClient.tokenLogin(tokenConfig)

Configuration Options

Making Outbound Calls

// Create a new outbound call
telnyxClient.call.newInvite(
    callerName = "John Doe",
    callerNumber = "+15551234567",
    destinationNumber = "+15559876543",
    clientState = "my-custom-state"
)

Receiving Inbound Calls

Listen for socket events using SharedFlow (recommended):

lifecycleScope.launch {
    telnyxClient.socketResponseFlow.collect { response ->
        when (response.status) {
            SocketStatus.ESTABLISHED -> {
                // Socket connected
            }
            SocketStatus.MESSAGERECEIVED -> {
                response.data?.let { data ->
                    when (data.method) {
                        SocketMethod.CLIENT_READY.methodName -> {
                            // Ready to make/receive calls
                        }
                        SocketMethod.LOGIN.methodName -> {
                            // Successfully logged in
                        }
                        SocketMethod.INVITE.methodName -> {
                            // Incoming call!
                            val invite = data.result as InviteResponse
                            // Show incoming call UI, then accept:
                            telnyxClient.acceptCall(
                                invite.callId,
                                invite.callerIdNumber
                            )
                        }
                        SocketMethod.ANSWER.methodName -> {
                            // Call was answered
                        }
                        SocketMethod.BYE.methodName -> {
                            // Call ended
                        }
                        SocketMethod.RINGING.methodName -> {
                            // Remote party is ringing
                        }
                    }
                }
            }
            SocketStatus.ERROR -> {
                // Handle error: response.errorCode
            }
            SocketStatus.DISCONNECT -> {
                // Socket disconnected
            }
        }
    }
}

Call Controls

// Get current call
val currentCall: Call? = telnyxClient.calls[callId]

// End call
currentCall?.endCall(callId)

// Mute/Unmute
currentCall?.onMuteUnmutePressed()

// Hold/Unhold
currentCall?.onHoldUnholdPressed(callId)

// Send DTMF tone
currentCall?.dtmf(callId, "1")

Handling Multiple Calls

// Get all active calls
val calls: Map<UUID, Call> = telnyxClient.calls

// Iterate through calls
calls.forEach { (callId, call) ->
    // Handle each call
}

Push Notifications (FCM)

1. Setup Firebase

Add Firebase to your project and get an FCM token:

FirebaseMessaging.getInstance().token.addOnCompleteListener { task ->
    if (task.isSuccessful) {
        val fcmToken = task.result
        // Use this token in your login config
    }
}

2. Handle Incoming Push

In your FirebaseMessagingService:

class MyFirebaseService : FirebaseMessagingService() {
    override fun onMessageReceived(remoteMessage: RemoteMessage) {
        val params = remoteMessage.data
        val metadata = JSONObject(params as Map<*, *>).getString("metadata")
        
        // Check for missed call
        if (params["message"] == "Missed call!") {
            // Show missed call notification
            return
        }
        
        // Show incoming call notification (use Foreground Service)
        showIncomingCallNotification(metadata)
    }
}

3. Decline Push Call (Simplified)

// The SDK now handles decline automatically
telnyxClient.connectWithDeclinePush(
    txPushMetaData = pushMetaData,
    credentialConfig = credentialConfig
)
// SDK connects, sends decline, and disconnects automatically

Android 14+ Requirements

<service
    android:name=".YourForegroundService"
    android:foregroundServiceType="phoneCall"
    android:exported="true" />

Call Quality Metrics

Enable metrics to monitor call quality in real-time:

val credentialConfig = CredentialConfig(
    // ... other config
    debug = true  // Enables call quality metrics
)

// Listen for quality updates
lifecycleScope.launch {
    currentCall?.callQualityFlow?.collect { metrics ->
        println("MOS: ${metrics.mos}")
        println("Jitter: ${metrics.jitter * 1000} ms")
        println("RTT: ${metrics.rtt * 1000} ms")
        println("Quality: ${metrics.quality}")  // EXCELLENT, GOOD, FAIR, POOR, BAD
    }
}

AI Agent Integration

Connect to a Telnyx Voice AI Agent without traditional SIP credentials:

1. Anonymous Login

telnyxClient.connectAnonymously(
    targetId = "your_ai_assistant_id",
    targetType = "ai_assistant",  // Default
    targetVersionId = "optional_version_id",
    userVariables = mapOf("user_id" to "12345")
)

2. Start Conversation

// After anonymous login, call the AI Agent
telnyxClient.newInvite(
    callerName = "User Name",
    callerNumber = "+15551234567",
    destinationNumber = "",  // Ignored for AI Agent
    clientState = "state",
    customHeaders = mapOf(
        "X-Account-Number" to "123",  // Maps to {{account_number}}
        "X-User-Tier" to "premium"    // Maps to {{user_tier}}
    )
)

3. Receive Transcripts

lifecycleScope.launch {
    telnyxClient.transcriptUpdateFlow.collect { transcript ->
        transcript.forEach { item ->
            println("${item.role}: ${item.content}")
            // role: "user" or "assistant"
        }
    }
}

4. Send Text to AI Agent

// Send text message during active call
telnyxClient.sendAIAssistantMessage("Hello, I need help with my account")

Custom Logging

Implement your own logger:

class MyLogger : TxLogger {
    override fun log(level: LogLevel, tag: String?, message: String, throwable: Throwable?) {
        // Send to your logging service
        MyAnalytics.log(level.name, tag ?: "Telnyx", message)
    }
}

val config = CredentialConfig(
    // ... other config
    logLevel = LogLevel.ALL,
    customLogger = MyLogger()
)

ProGuard Rules

If using code obfuscation, add to proguard-rules.pro:

-keep class com.telnyx.webrtc.** { *; }
-dontwarn kotlin.Experimental$Level
-dontwarn kotlin.Experimental
-dontwarn kotlinx.coroutines.scheduling.ExperimentalCoroutineDispatcher

Troubleshooting

Resources

• Official Documentation
• Push Notification Setup
• GitHub Repository