Panasonic KX-NS1000 User Manual page 41

3-7 Two-way Record / Transfer Feature (3)
Two-way Recorded Message Save mode
You can select whether two-way recording sessions are saved in the mailboxes as "old"
or "new" messages for each mailbox, through COS programming.
Setup -> UM Configuration -> 2 Class of Service
* The mailbox at which a message is saved should be set to the corresponding COS.
Mailbox Tab
"Two-way Recorded Message Save Mode" for each COS
- Save as New
- Save as Old (Default)