Well, I'm not much of expert with either but there is an Accounts list in Calendar's preferences for selecting a server account. The default is iClouds which in turn defaults to your Apple ID or eMail address. If that is active then most likely it will go to FaceTime. An Exchange address can be configured in a new account. I'm guessing that is where you can set it up to work differently. Never used this option so I don't know what would happen if you made a different account. There are setup options for almost everything including Yahoo, Google, Exchange, CalDav, etc.
In FaceTime you can provide a recipient with phone number or email address so that when you click on the entry it will dial the number or number associated with the email address. However, it must be in your Contacts list. I don't know what happens after that because FaceTime won't be able to create a connection with WebEx.
You can also configure Internet Accounts preferences much like configuring Calendar. Lastly, check Contacts which holds names, addresses, email address, telephone numbers, etc. that may feed to all other applications.
Best that comes to mind, I'm afraid. You can also call Cisco's tech support. They know a lot about Mac networking.