1.25 Networking Features
202 Feature Guide
line group carrying the outgoing call.
When making TIE-to-CO line calls, the incoming TIE line call is received by one CO line of a
PBX, and the outgoing CO line call is made using another CO line. Both lines belong to CO
line groups, and both groups have a Class of Service (COS), therefore, Toll Restriction (TRS)
can be used to allow certain TIE-to-CO line calls to be made while others are prohibited. (→
1.8.1 Toll Restriction (TRS)) These restrictions are based on the COS of the CO line group
carrying the incoming TIE line call.
Additionally, the outgoing CO line group can be programmed to completely block all calls from
being made when incoming TIE line calls are received on CO line groups of a certain COS.
(External Call Block)
Note that it is possible for a PBX user to bypass these restrictions by using Direct Inward
System Access (DISA). By making a TIE line call to a floating extension number used by the
DISA feature of the other PBX, then using Walking COS (→ 1.8.4 Walking COS) or Verified
Code Entry (→ 1.8.5 Verified Code Entry) through DISA, a PBX user can make a call that is
normally restricted, provided his or her COS is authorized to make the call.
[Programming Example: CO Line Group COS, PBX-2]
[Programming Example: External Call Block, PBX-2]
[Example of TIE-to-CO Line Call, Blocked/Restricted Based on COS]
CO Line
Group No.
1
2
COS
No.
3
2
COS of
Incoming
CO Line
Group
COS 1
COS 2
COS 3
CO Line
Group 1
Block
CO Line
Group 3
Block
Block
CO Line
Group 64
Block
Block
CO Line Group of Outgoing Calls
...
CO Line
Group 2
Block
Block
Block
Makes a TIE-to-CO line call
Outside Party
CO Line Grp. 1
(COS: 3)
CO Line
Grp. 3
Private Network
Extn. 1001
Telephone
Company
PBX-2PBX-1
To Next Page
Loading...
