Panasonic KX-T336 System Reference Manual page 224

Assuming that your telephone system is located
in the area, Area Code (AC)=200, Office Code
(OC)=320, accordingly, your CO number is (1) +
200 + 320 + XXXX.
Determine the Restriction Level of each AC and
OC respectively according to the TRLE of each
extension user (Table 1).
Table 2 Restriction Level of each AC and OC
the boundaries of Area Code
- - - - - - - - -
the boundaries of Office Code
3-C-17