An Engineer Must Extend the Corporate Phone System to Mobile

Multiple Choice

An engineer must extend the corporate phone system to mobile users connecting through the internet with their own devices. One requirement is to keep that as simple as possible for end users. Which infrastructure element achieves these goals?

A) Cisco Express Mobility
B) Cisco Expressway-C and Expressway-E
C) Cisco Unified Border Element
D) Cisco Unified Instant Messaging and Presence