A CUCM administrator has configured a Cisco IOS CFB using a Cisco 2921 router and encounters an issue. What is the root cause?
A. The CFB sent the registration message twice
B. The CFB protocol version is not compatible with this CUCM version
C. CUCM has not received the first keepalive message from CFB
D. Device type in CUCM does not match the one configured on Cisco IOS
E. CUBE_CFB name was entered incorrectly in CUCM database
