Which two configurations must be made to allow calls to or from an IP phone at a branch location to complete to a destination outside of that branch?

IP WAN failure has occurred. Which two configurations must be made to allow calls to or from an IP phone at a branch location to complete to a destination outside of that branch? (Choose two.)
A. Survivable Remote Site Telephony is configured on the branch router.
B. LAN failover configuration is set to Survivable Remote Site Telephony.
C. Call Forward UnRegistered option is configured on each branch phone profile.
D. POTS WAN failover is set to Survivable Remote Site Telephony.
E. An ISDN is configured as a primary survivable backup site