What is PInvoke?
PInvoke stands for Platform Invocation. It is a feature in Microsoft .NET Framework that allows the developer to make Native calls from Managed Code.
Can I use PInvoke or Native calls in Windows Phone App?
For the Windows Phone App to clear the certification in the Windows Phone Store, the Windows phone app (7.1) should not use P/Invoke or COM interoperability. If the App is a Windows Phone 8 app, then the app should use only the Win32 and COM API which is defined by the Windows Phone 8 SDK.