Twilio Client Android SDK

Overview

Want your Android app to make and receive calls? Look no further!

Twilio Client Android is a Java library for Android that enables voice communications with landlines or other Twilio Client devices, including web browsers and other mobile devices.

Install the Android SDK

To install the latest Client SDK library add the following configuration to your build.gradle file:

allprojects {
  repositories {
     jcenter()
  }
}

dependencies {
  // The Client SDK resides on jCenter
  compile 'com.twilio:client-android:1.2.14'
}

Enable Microphone Permissions

In order to target Android API level 23 or later, you will need to ensure that your application requests runtime permissions for microphone access. To do this, perform the following two steps:

First, add the following to your Android Manifest file:

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

Second, request microphone permissions from within your application code:

ActivityCompat.requestPermissions(this,
    new String[]{Manifest.permission.RECORD_AUDIO}, MIC_PERMISSION_REQUEST_CODE);
}

See the Official Android Documentation for more details.

ProGuard Exception

Add the following line to your proguard-project.txt file.

# Twilio Client
-keep class com.twilio.** { *; }

# Apache HttpClient
-dontwarn org.apache.http.**

This ensures that the Twilio Client library is not removed by ProGuard.

Architecture

There are three major pieces in a Twilio Client app:

  1. Your Android app that uses the Twilio Client Android library
  2. A server to grant capabilities to your Client app as well as to serve up TwiML and/or make Twilio REST API calls
  3. Twilio's cloud services to handle the telephony and process TwiML and/or REST API calls

Twilio Client Android SDK Architecture

Client-side Classes

The primary class for connecting to Twilio services from your app is Device. This class coordinates service authorization with Twilio, listens for incoming connections, and establishes outgoing connections. An instance of this class is created using a "capabilty token", described in the next section.

Connections to Twilio, either incoming or outgoing, are represented by instances of the class Connection.

In addition, status callbacks are provided to objects that implement the listener interfaces DeviceListener and ConnectionListener.

Server-side Security: Capability Tokens

The Twilio Client SDK uses a capability token to sign communications from your Android app to Twilio. These tokens are created by you on your server and allow you to specify what capabilities are going to be available to your app, such as whether it can receive incoming connections, make outgoing connections, etc. These tokens always have an expiration, which means all tokens have a limited lifetime to protect you from abuse. It is up to you to determine how often these tokens must be refreshed.

Twilio capability tokens are based on the JSON Web Token standard. They can be generated with our helper libraries that come in a variety of languages.

For the security of your Twilio account, you should not embed a Capability Token or your Twilio Auth Token as strings in the app you submit to the Google Play Store.

Class Reference