Panasonic KX-TD500 System Reference Manual page 333

Routing Procedure 2: Routing Flow Chart
(1) When a tie call is made by an extension user in your PBX
Calling to Extension
(Note)
TRLE = Toll Restriction Level of Extension
TRLT = Toll Restriction Level of Trunk Group
Analyzing extension dialed number
Extension
No
Own Ext. No?
Yes
Is first 3-disit
registered in the
table?
Compares TRLE
of extension with
TRLT of trunk
group according
to hunt sequence.
3-F-73
Tie trunk
No
Yes
TRLE < TRLT
TRLE TRLT
Calling to Tie Reorder Tone
CO
Calling to CO