Panasonic NS1000 Manual page 215

1.2 System Firmware Download
A Slave PBX can also obtain it's firmware from a MASTER
Manual Download (4) - Download from MASTER PBX
Select the Download Location
Select the file to download
(Only most recently downloaded files are displayed)
NB: PCMPR file is shown here, but CS, UT, NT and LPR firmware is also available to download