A company has decided to upgrade its legacy phone system to VoIP. The new phones will download the
configurations from a TFTP server each time they boot up. Which of the following firewall ports must be opened
to ensure the phones can communicate with the server?

A.
20

B.
53

C.
69

D.
161

Explanation:
https://en.wikipedia.org/wiki/Trivial_File_Transfer_Protocol