Remote users connect to a VPN concentrator for video conferences. Because all email, voice mail, telephony, presence, and messaging has been integrated, a list of security measure has been developed. Which of the following measures does not address unified communications security?

A. creating presence groups
B. restricting IM protocols to the internal network
C. implementing single sign on
D. restrict access to services to local users and VPN users

C
Explanation While single on simplifies the management of passwords by usersm it does not specifically address unified communications issues.