You are the Microsoft Lync administrator for your company.
An employee needs to use Lync Online to call two external Skype contacts simultaneously. The
employee can only call one contact at a time.
What should you advise the employee to do?

A.
Turn on external communication

B.
Check the formatting of her user name

C.
Invite contacts to a Lync Meeting

D.
Verify that the Skype users are signed in to a Microsoft Account

Explanation:
Skype users must be signed in with their Microsoft account (formerly Windows Live ID).
Let Lync Online users communicate outside your organization [Small Business]
https://support.office.com/en-ca/article/Let-Lync-Online-users-communicate-outside-yourorganization-Small-Business-7f488f09-f004-4db5-aec5-01c262aa3d34?ui=en-US&rs=en-CA&ad=CA