In a TDM PBXto Cisco Unified Communications Manager migration, which three things must be verified from the LAN perspective before IP telephony can be deployed? (Choose three.)

A.
the type of wiring in the office

B.
the number of PSTN connections needed

C.
the number of public IP addresses available

D.
the amount of rack space in the equipment rack

E.
the amount of power that is available to support new LAN switches