实时音视频SDK，如何实现类似微信的纯语音通话功能？

public class TRTCMainActivity extends Activity{

    private TRTCCloud trtcCloud;              /// TRTC SDK 实例对象
    private TRTCCloudListener trtcListener;    /// TRTC SDK 回调监听

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ....
        trtcListener = new TRTCCloudListenerImpl(this);
        trtcCloud = TRTCCloud.sharedInstance(this);
        trtcCloud.setListener(trtcListener);        
    }

    //静态内部类，重写监听事件
    static class TRTCCloudListenerImpl extends TRTCCloudListener {

        private WeakReference<TRTCMainActivity> mContext;
        public TRTCCloudListenerImpl(TRTCMainActivity activity) {
            super();
            mContext = new WeakReference<>(activity);
        }
     @Override
        public void onEnterRoom(long elapsed) {
            //TODO
        }
     @Override
        public void onExitRoom(int reason) {
            //TODO
        }
     @Override
        public void onError(int errCode, String errMsg, Bundle extraInfo) {
            //TODO
        }
     @Override
        public void onWarning(int warningCode, String warningMsg, Bundle extraInfo) {
            //TODO
        }
     @Override
        public void onUserEnter(String userId) {
            //TODO
        }
    }

    // 销毁 trtcCloud 实例
    @Override
    protected void onDestroy() {
        super.onDestroy();
        //销毁 trtc 实例
        if (trtcCloud != null) {
            trtcCloud.setListener(null);
            trtcCloud.destroy();
        }
        trtcCloud = null;
    }
}

void enterRoom() {

     // 预览前配置默认参数
     setTRTCCloudParam();

    //TRTCParams 定义参考头文件TRTCCloudDef.java
    trtcParams = new TRTCCloudDef.TRTCParams();
    trtcParams.sdkAppId = sdkappid;
    trtcParams.userId   = userid;
    trtcParams.userSig  = usersig;
    trtcParams.roomId   = 908; //输入你想进入的房间
    trtcCloud.enterRoom(trtcParams, TRTC_APP_SCENE_VIDEOCALL);
}

void setTRTCCloudParam() {
     // 大画面的编码器参数设置
        // 设置视频编码参数，包括分辨率、帧率、码率等等，这些编码参数来自于 TRTCSettingDialog 的设置
        // 注意（1）：不要在码率很低的情况下设置很高的分辨率，会出现较大的马赛克
        // 注意（2）：不要设置超过25FPS以上的帧率，因为电影才使用24FPS，我们一般推荐15FPS，这样能将更多的码率分配给画质
/*        TRTCCloudDef.TRTCVideoEncParam encParam = new TRTCCloudDef.TRTCVideoEncParam();
        encParam.videoResolution = settingDlg.getResolution();
        encParam.videoFps = settingDlg.getVideoFps();
        encParam.videoBitrate = settingDlg.getVideoBitrate();
        encParam.videoResolutionMode = TRTCCloudDef.TRTC_VIDEO_RESOLUTION_MODE_PORTRAIT;
        trtcCloud.setVideoEncoderParam(encParam);*/

        // 不开启视频采集预览
       /* TXCloudVideoView localVideoView = mVideoViewLayout.getCloudVideoViewByIndex(0);
        localVideoView.setUserId(trtcParams.userId);
        localVideoView.setVisibility(View.VISIBLE);
        trtcCloud.setLocalViewFillMode(TRTCCloudDef.TRTC_VIDEO_RENDER_MODE_FILL);
        trtcCloud.startLocalPreview(true, localVideoView);*/
        //只开启音频采集
        trtcCloud.startLocalAudio();
        trtcCloud.setGSensorMode(TRTCCloudDef.TRTC_GSENSOR_MODE_UIFIXLAYOUT);
}

private void exitRoom() {
    if (trtcCloud != null) {
        trtcCloud.exitRoom();
    }
}
...
@Override
public void onExitRoom(int reason) {
    TRTCMainActivity activity = mContext.get();
    if (activity != null) {
        activity.finishActivity();
    }
}