You are working with a client who is interested in deploying a distributed IP telephony call-processing solution among the three corporate campuses. Each campus will have a Cisco Unified CallManager cluster and a gateway to the PSTN. Which three steps are required for a successful gatekeeper deployment? (Choose three.)

A.
determining if each zone will be supported by more than one gatekeeper

B.
determining the intrasite modem and fax traffic patterns

C.
ensuring the correct location of voice gateways in the network

D.
provisioning a common codec for all WAN connections

E.
implementing the correct WAN topology

F.
determining if gatekeeper redundancy or high availability is required