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

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 anOpenReceiveChannelmessage, the I 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/IP-based) communication for audio transmissions.