Skype in C# (Visual Studio 2015)

Question

I am writing a Database system in C# and Visual Studio 2015 (WPF). I have a table of users that lists their names and their internal telephone numbers. There are two scenarios we would like to achieve, both being best-case;

1. A user is able to click on a phone number in the DataGrid and the dialing process is started in C#, which calls the Skype for Business program and dials the employee through Skype for Business.
2. The user clicks on the phone number in the DataGrid, and the call is automatically dialed out ausing a Mitel phone system, allowing the user to dial any employee our company they wish to contact from within the Database system itself.

I understand these are probably two completely different systems but currently we are stuck for either. I've tried using the SKYPE4COM API for C# but as far as I can see it is now deprecated and unusable.