Panasonic KX-NS500 Installation Manual page 121

When you select E1 use
Indication
STATUS
Maximum Cabling Distance of Extension Connection
The maximum length of the extension cable that connects the PRI port is shown below:
Colour Description
Green Off : All Ports OUS or Fault
On: At lease one port is In Service
Flashing (60 times per minute): Normal (a port is in use)
CAT 5: Under 200 m
4.5.2 PRI30/E1 Card (KX-NS5290CE)
Installation Manual 121