Using Platform Specifics from Xamarin.Forms

Most of an App we wish to write on multiple platforms is generic and I believe can be handled by the Xamarin.Forms abstractions of the UI.

However we need to do three things which may be specific to each platform

1. Dial a telephone number
2. Open a TCP/IP session with a server
3. Obtain Location information

How are these handled within the context of Xamarin.Forms ?, How do I drill down and access these.

Thanks