You can change the existing username when you are giving the account to a different user. However, the new username will affect the following.

The following will be reflected with the new username

• Username displayed on MiiTel Phone
• Username displayed in the aggregation results of the user
• Username in the call history list (MiiTel won't reflect the new username in the new Call History List's past call histories)
• Username in the CSV file that is created in storage (MiiTel won't reflect the new username in the CSV file that was created before the name change)