[Visual C#] Connect a Windows Phone (8.1) to an Arduino

Hello, I want to write an app in Visual C# to send data from a smartphone with Windows Phone 8.1 (Lumia 630) to an Arduino board via bluetooth connection.

On the PC I've used the class SerialPort of .NET, but on WP I search the best way.

Anyone can help me?

Thanks!

but on WP I search the best way.

No, you don't. You've already made up your mind:

via bluetooth connection.