Start a Voice Call

Use this guide to quickly start a basic voice call with the Agora Voice SDK for Windows.

The following figure shows the workflow to integrate into your app in order to add Voice Call functionality.

As shown in the figure, the workflow for adding Voice Call in your project is as follows:

1. Retrieve a token A token is the credential that authenticates a user when your app client joins a channel. In a test or production environment, your app client retrieves tokens from a server in your security infrastructure.

2. Join a channel Call joinChannel to create and join a channel. App clients that pass the same channel name join the same channel.

3. Publish and subscribe to audio in the channel After joining a channel, the app client automatically publishes and subscribes to audio and video in the channel.

For an app client to join a channel, you need the following information:

• The App ID: A randomly generated string provided by Agora for identifying your app. You can get the App ID from Agora Console.
• The user ID: The unique identifier of a user. You need to specify the user ID yourself, and ensure that it is unique in the channel.
• A token: In a test or production environment, your app client retrieves tokens from a server in your security infrastructure. For this page, you use a temporary token with a validity period of 24 hours that you retrieve from Agora Console.
• The channel name: A string that identifies the channel for the voice call.

We provide the open-source sample projects that implement the video call on GitHub:

• Agora-Windows-Tutorial-1to1
• GroupVideoCall-Windows-MFC

Before implementing a voice call, you can download the sample projects and refer to the source code.

• Microsoft Visual Studio 2017 or later
• A Windows device running Windows 7 or later
• A valid Agora account. (Sign up for free)

Open the specified ports in Firewall Requirements if your network has a firewall.

In this section, we will create a Windows project and integrate the SDK into the project.

Now, let's build a Windows project from scratch. Skip to Integrate the SDK if a Windows project already exists.

Create a Windows project

1. Open Microsoft Visual Studio and click Create new project.
2. On the New Project panel, choose MFC Application as the project type, input the project name, choose the project location, and click OK.
3. On the MFC Application panel, choose Application type > Dialog based, and click Finish.

Follow these steps to integrate the Agora Voice SDK into your project.

1. Configure the project files

• Go to SDK Downloads, download the latest version of the Agora SDK for Windows, and unzip the downloaded SDK package.
• Copy the x86 or x86_64 folder of the downloaded SDK package to your project files according to your development environment.

2. Configure the project properties

Right-click the project name in the Solution Explorer window, click Properties to configure the following project properties, and click OK.

• Go to the C/C++ > General > Additional Include Directories menu, click Edit, and input $(SolutionDir)include in the pop-up window.
• Go to the Linker > General > Additional Library Directories menu, click Edit, and input $(SolutionDir) in the pop-up window.
• Go to the Linker > Input > Additional Dependencies menu, click Edit, and input agora_rtc_sdk.lib in the pop-up window.

This section introduces how to use the Agora SDK to make a voice call. The following figure shows the API call sequence of a basic one-to-one voice call.

Create the user interface (UI) for the one-to-one voice call in your project. Skip to Initialize IRtcEngine if you already have a UI in your project.

If you are implementing a voice call, we recommend adding the elements into the UI:

• The end-call button

When you use the UI setting of the demo project, you can see the following interface:

Create and initialize the IRtcEngine object before calling any other Agora APIs.

In this step, you need to use the App ID of your project. Refer to Get Started With Agora to create an Agora project and get the App ID in Console.

Call the createAgoraRtcEngine method and the initialize method, and pass in the App ID to initialize the IRtcEngine object.

You can also listen for callback events, such as when the local user joins the channel, and when the local user leaves the channel.

CAgoraObject *CAgoraObject::GetAgoraObject(LPCTSTR lpAppId)

{

if (m_lpAgoraObject == NULL)

m_lpAgoraObject = new CAgoraObject();

if (m_lpAgoraEngine == NULL)

// Create the instance.

m_lpAgoraEngine = (IRtcEngine *)createAgoraRtcEngine();

if (lpAppId == NULL)

return m_lpAgoraObject;

RtcEngineContext ctx;

ctx.eventHandler = &m_EngineEventHandler;

#ifdef UNICODE

char szAppId[128];

::WideCharToMultiByte(CP_ACP, 0, lpAppId, -1, szAppId, 128, NULL, NULL);

// Input your App ID.

ctx.appId = szAppId;

#else

ctx.appId = lpAppId;

#endif

// Initialize the RtcEngine object.

m_lpAgoraEngine->initialize(ctx);

return m_lpAgoraObject;

}

// Inherit the events and callbacks of IRtcEngineEventHandler.

class CAGEngineEventHandler :

public IRtcEngineEventHandler

{

public:

CAGEngineEventHandler(void);

~CAGEngineEventHandler(void);

void SetMsgReceiver(HWND hWnd = NULL);

HWND GetMsgReceiver() {return m_hMainWnd;};

// Listen for the onJoinChannelSuccess callback.

// This callback occurs when the local user successfully joins the channel.

virtual void onJoinChannelSuccess(const char* channel, uid_t uid, int elapsed);

// Listen for the onLeaveChannel callback.

// This callback occurs when the local user successfully leaves the channel.

virtual void onLeaveChannel(const RtcStats& stat);

// Listen for the onUserOffline callback.

// This callback occurs when the remote user leaves the channel or drops offline.

virtual void onUserOffline(uid_t uid, USER_OFFLINE_REASON_TYPE reason);

private:

HWND m_hMainWnd;

};

After initializing the IRtcEngine object, you can call the joinChannel method to join a channel. In this method, set the following parameters:

• channelName: Specify the channel name that you want to join.

• token: Pass a token that identifies the role and privilege of the user. You can set it as one of the following values:

  • A temporary token generated in Console. A temporary token is valid for 24 hours. For details, see Get a Temporary Token. When joining a channel, ensure that the channel name is the same with the one you use to generate the temporary token.
  • A token generated at the server. This applies to scenarios with high-security requirements. For details, see Generate a token from Your Server. When joining a channel, ensure that the channel name and uid is the same with those you use to generate the token.

• If your project has enabled the app certificate, ensure that you provide a token.
• Ensure that you do not set token as "".

• uid: ID of the local user that is an integer and should be unique. If you set uid as 0, the SDK assigns a user ID for the local user and returns it in the onJoinChannelSuccess callback.
  Once the user joins the channel, the user subscribes to the audio streams of all the other users in the channel by default, giving rise to usage and billing calculation. If you do not want to subscribe to a specified stream or all remote streams, call the mute methods accordingly.

For more details on the parameter settings, see joinChannel.

BOOL CAgoraObject::JoinChannel(LPCTSTR lpChannelName, UINT nUID,LPCTSTR lpToken)

{

int nRet = 0;

#ifdef UNICODE

CHAR szChannelName[128];

::WideCharToMultiByte(CP_UTF8, 0, lpChannelName, -1, szChannelName, 128, NULL, NULL);

char szToken[128];

::WideCharToMultiByte(CP_UTF8, 0, lpToken, -1, szToken, 128, NULL, NULL);

if(0 == _tcslen(lpToken))

nRet = m_lpAgoraEngine->joinChannel(NULL, szChannelName, NULL, nUID);

else

// Join a channel with a token.

nRet = m_lpAgoraEngine->joinChannel(szToken, szChannelName, NULL, nUID);

#else

if(0 == _tcslen(lpToken))

nRet = m_lpAgoraEngine->joinChannel(NULL, lpChannelName, NULL, nUID);

else

nRet = m_lpAgoraEngine->joinChannel(lpToken, lpChannelName, NULL, nUID);

#endif

if (nRet == 0)

m_strChannelName = lpChannelName;

return nRet == 0 ? TRUE : FALSE;

}

Call the leaveChannel method to leave the current call according to your scenario, for example, when the call ends, when you need to close the app, or when your app runs in the background.

BOOL CAgoraObject::LeaveChannel()

{

m_lpAgoraEngine->stopPreview();

// Leave the current channel.

int nRet = m_lpAgoraEngine->leaveChannel();

return nRet == 0 ? TRUE : FALSE;

}

void CAgoraObject::CloseAgoraObject()

{

if(m_lpAgoraEngine != NULL)

// Release the IRtcEngine object.

m_lpAgoraEngine->release();

if(m_lpAgoraObject != NULL)

delete m_lpAgoraObject;

m_lpAgoraEngine = NULL;

m_lpAgoraObject = NULL;

}

Run the project on your Windows device. You can hear the remote user when you successfully start a one-to-one voice call in your app.

When integrating the Agora Voice SDK, you can also refer to the following articles:

• How can I set the log file?