Panasonic NS1000 Manual page 218

Devices can be upgraded automatically at a specified time.
System Upgrade (2) - Timed
Select the upgrade
target (Device)
NB: Once devices have received the firmware updates, they will automatically re-boot – Take care at busy times!
If the upgrade process is made via a SLAVE Unit, only the SLAVE and Terminals registered to the SLAVE are upgraded.
1.3 PBX System Firmware Upgrade (2)
Select the required 'Update Time'
Select 'Timed Update'