Yealink SIP-T48G - Manual (Page 113)

Basic Call Features
103
Incoming calls will be rejected automatically, and the touch screen will prompt "n
New Missed Call(s)" ("n" indicates the number of the missed calls).
Note
To configure the DND authorized numbers via web user interface:
1. Click on Features->Forward & DND.
2. Select Enable from the pull-down list of DND Emergency.
3. Enter the numbers in the DND Authorized Numbers field.
The prompt message displays only if Missed Call Log for the line is enabled. Missed call
log is configurable via web user interface at the path Account->Basic.
Do not disturb is local to the phone, and may be overridden by the server settings. For
more information, contact your system administrator.