- Open up Skype for Business, near the top you will see 4 headings titled "GROUPS" "STATUS" "RELATIONSHIPS" "NEW". To the right of that will be a person with a plus next to it. Click it.
- From there click onto the section that says "Add a contact not in my Organisation".
- Select the most relevant option.
- Enter the details (it is preferred to use an email address) for the external contact. Once you have found the correct person right click their name and add them to contacts list.
For information on how to create a Skype meeting through outlook please refer to this article.