Panasonic KEY TELEPHONE - Manual (Page 54)

5. Communicating Within Your Office
54 Key Telephone User Guide
2. Do one of the following
3. Replace the handset or press the ON/OFF key.
To cancel DND . . . Do . . .
For your extension Enter the Cancel DND code (default = 720).
For another extension
a. Enter the Cancel DND Set by Other Phone code
(default = 750).
b. Dial the extension number.