Your network has Lync Server 2010 deployed.
Certain telephone numbers in your number range are currently unassigned.
You need to ensure that when users call an unassigned telephone number, they hear a custom message.
What should you create?

A.
a call park

B.
a Response Group

C.
a Voice Policy

D.
an announcement service

Explanation:
http://blogs.technet.com/b/csps/archive/2011/03/03/snippetsannouncements.aspx