Which of the following does the auto-reg-ephone command configure a CME router to do?

A.
automatically assign an ephone to an IP phone

B.
automatically assign an ephone-dn to an ephone

C.
automatically assign an IP address to an IP phone

D.
automatically assign an IP phone to a hunt group

Explanation:
The auto-reg-ephone command configures a Cisco Unified Communications Manager Express (CME) router to
automatically assign an ephone to an IP phone. When an IP phone registers with a router that is configured
with the auto-reg-ephone command, the router will associate the Media Access Control (MAC) address of the
IP phone with the first unassigned ephone on the router. If all the ephones on the router are associated with IP
phones, the router will create a new ephone, provided that the number of configured ephones does not exceed
the value of the max ephone command. You can also manually assign an IP phone to an ephone by issuing the
mac-address mac-address command in ephone configuration mode, where mac-address is the MAC address
of the IP phone you want to assign to the ephone.
The auto assign command configures a CME router to automatically assign an ephone-dn to an ephone, not an
ephone to an IP phone. When an IP phone registers with a router that is configured with the auto assign
command, the router will associate button 1 on the IP phone’s ephone with an existing, unused ephone-dn. If
no ephone-dn is available, the phone will register but none of the phone’s buttons will be associated with
ephone-dn extensions. It is possible to assign multiple buttons on a phone with unique ephone-dns. Similarly, it
is possible to assign the same ephone-dn to more than one IP phone. However, when assigning multiple
ephone-dns to the same device or a single ephone-dn to multiple devices, you should ensure that ephone-dns
are correctly assigned in CME. Otherwise, calls to those ephone-dns could intermittently fail.
The auto-reg-ephone command does not configure a router to automatically assign an IP address to an IP
phone. A router that is configured as a Dynamic Host Configuration Protocol (DHCP) server automatically
assigns an IP address to an IP phone. The following partial output from the show running-config command
displays a DHCP server that is configured to distribute IP addressing information to IP phones:
ip dhcp excluded-address 192.168.14.1 192.168.14.9
ip dhcp pool IPPhones
network 192.168.14.0 255.255.255.0
default-router 192.168.14.1
option 150 ip 192.168.14.1
The auto-reg-ephone command does not configure a router to automatically assign an IP phone to a hunt
group. IP phones are associated with ephones, ephones are associated with ephone-dns, and ephone-dns are
manually assigned to hunt groups.

Cisco: Cisco Unified CME Commands: auto assign