Which two SCCP call signaling messages are initiated by Cisco Unified Communications Manager to
an IP phone? (Choose two.)

A.
SoftKeyEvent

B.
CloseReceiveChannelAck

C.
CallState

D.
KeypadButton

E.
OpenReceiveChannel

F.
Offhook

Explanation:
Upon receiving an OpenReceiveChannelmessage, the IP phone selects the UDP port number it wants
to use to receive RTP packets and reports this information to call manager.
With the SCCP protocol architecture, the majority of the H.323 processing power resides in an H.323
proxy — the Cisco CallManager. The end stations (IP phones) run the Skinny client, which consumes
less processing overhead. The client communicates with CallManager using connection-oriented
(TCP/IP-based) communication to establish a call with another H.323-compliant end station. Once
Cisco CallManager has established the call, the two H.323 end stations use connectionless (UDP/IPbased) communication for audio transmissions.