D-Link DVX-2000MS-10P - VoiceCenter IP Phone Sys 10P Quick Installation Manual page 11

Select one of the D-Link DPH-125MS IP Phones you just connected
and click Next to continue.
For this step, you will add a new user and assign that user to the
phone you just selected. Click Assign User to open the New User
screen.
11 D-Link VoiceCenter Quick Install Guide