You can add a new contact to the Contacts list, so it will appear with the rest of your existing contacts.
Click the Calls button on the App bar.
Click Contacts in the List pane.
All your contacts are displayed in a single list.
You can add contacts within your organization or outside of it. However, you'll only be able to call people outside of your organization with a supported calling plan.
Click Add Contact.
Enter a contact's name.
If the name you entered is in your organization, a suggestion will appear in a pop-up. If that is who you want to add, you can select them from the list to automatically add their information.
Otherwise, you can continue adding their information manually.