What two signaling methods between the IP phone and the Cisco Unified Communications Manager Express are available for usage?

You are CCNA VOICE associate in Certkey.com.You are planning stages of deploying a Cisco Unified Communications solution. Previously, Certkey was leasing a traditional PBX system from the telcom and very little experience with voice. What two signaling methods between the IP phone and the Cisco Unified Communications Manager Express are available for usage?

A.
H.323

B.
SCCP

C.
MGCP

D.
SIP