Passing Small bits of data to a WPF applicatoin from Office Outlook

I have a call manager application that is developed under WPF. I want to
create an Outlook addin that will call my call manager app and pass a
phone
number as well as the contact name to. The call manager will then make a
call.

I have no idea what to use to pass this from one application to
another...Windows Messaging, Command Line interface...no idea.

Thanks,

Steve