Which solution is needed to enable presence and extension mobility to branch office phones during a WAN failure?
A. SRST with MGCP fallback
B. SRST without MGCP fallback
C. Cisco Unified Communications Manager Express in SRST mode
D. SRST with VoIP dial peers to Cisco Unified Communications Manager Express
CUCM Express in Cisco Unified SRST mode provides more features to a smaller maximum number of IP Phones by falling back to CUCM Express mode. The main feature enhancements include Presence, Cisco Extension Mobility, and support of local voice-mail integrations.