All of your department’s IP phones are connected to a switch that does not support PoE. The IP phones have
all been manually configured with IP addressing information. Another administrator power cycles the switch
without warning. No calls are in progress.
Which of the following is most likely to occur? (Select the best answer.)

A.
The IP phones will power down until the switch restarts.

B.
The IP phones will not be affected by the power cycle.

C.
The IP phones will disappear from the UCM configuration.

D.
The IP phones will reset but retain IP configuration information.

Explanation:
Most likely, the IP phones will reset but retain IP configuration information when the administrator power cycles
the switch because, in this scenario, the IP addressing information has been manually configured on each IP
phone. When an IP phone is disconnected from Cisco Unified Communications Manager (UCM), the phone will
automatically reset in an attempt to reestablish communication. Therefore, if an IP phone suddenly resets or is
continuously attempting to register with UCM, it is important to first verify the phone’s connectivity to the
network switch.
The IP phones will not disappear from the UCM configuration. You can verify that an IP phone exists in the
UCM by clicking Device > Phone > Find in UCM Administration and searching for the particular IP phone’s
Media Access Control (MAC) address. The IP phone will no longer be registered with UCM when it loses
connectivity. However, the IP phone’s record in the UCM configuration will remain there.
The IP phones will not power down until the switch restarts, because the switch in this scenario does not
support Power over Ethernet (PoE). Therefore, the IP phones in this scenario must be connected to individual
power supplies in order to obtain power.
The IP phones will be affected by the power cycle. In addition to registration problems, IP configuration
problems, and Trivial File Transfer Protocol (TFTP) configuration problems, IP phones that are powered directly
from a switch by using PoE will not be able to receive power until the switch has restarted.

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cuipph/7905g_7912g/5_0/sip/english/administration/
guide/5_0/LowPtrb.html#wp1092158