how to play audio through earpiece only in windows phone 8 application - windows-phone-8

Question

I have tried with AudioRoutingManager class...but i got unauthorizedaccess exception.
here is my code
AudioRoutingManager audioRouting = AudioRoutingManager.GetDefault();
public AudioRoutingEndpoint ChangeAudioRoute()
{
var currentEndPoint= audioRouting.GetAudioEndpoint();
switch (currentEndPoint)
{
case AudioRoutingEndpoint.Earpiece:
case AudioRoutingEndpoint.Default:
return AudioRoutingEndpoint.Speakerphone;
case AudioRoutingEndpoint.Speakerphone:
return AudioRoutingEndpoint.Earpiece;
default:
throw new OperationCanceledException();
}
}
public void SetAudioRoute()
{
audioRouting.SetAudioEndpoint(this.ChangeAudioRoute());
}

Answer 1

The APIs in the Windows.Phone.Media.Devices namespace require the ID_CAP_AUDIOROUTING and the ID_CAP_VOIP capability. (Add this to your manifest)
Also, it's only possible to change the audio routing while in a active VOIP call.
Additionally, you need to do the audio routing in your background VOIP process, and not in the foreground process.

Answer 2

Old question but now I know the answer.
Two things which you need to do:
Tag the audio in question as "communications"
How to do this depends on what API you're using. It could be as simple as . Or you might have to call IAudioClient2::SetClientProperties with an AudioClientProperties structure whose AudioClientProperties.eCategory = AudioCategory_Communications.
Tag your app as either a "voice over IP" app or a "voicemail" app
You should add file called WindowsPhoneReservedAppInfo.xml to your project with the following contents:
<?xml version="1.0" encoding="utf-8"?>
<WindowsPhoneReservedAppInfo xmlns="http://schemas.microsoft.com/phone/2013/windowsphonereservedappinfo">
<SoftwareCapabilities>
<SoftwareCapability Id="ID_CAP_VOIP" />
</SoftwareCapabilities>
</WindowsPhoneReservedAppInfo>
Look for more detailed explanation here:
Playing audio to the earpiece from a Windows Phone 8.1 universal app