Panasonic KX-NS1000 Feature Manual page 319

[Example]
Gateway Settings List
1. V-IPGW(1): GW Group-1
2. V-IPGW(2): GW Group-1
3. V-IPGW(3): GW Group-2
4. V-IPGW(4): GW Group-2
When "123XXX" is dialed, the call is routed to GW Group-1. However the lowest-numbered device
(V-IPGW(1)) is busy or not available, so the call is rerouted to V-IPGW(2).
Common Extension Numbering for Multiple PBXs
Multiple PBXs in separate locations, connected in an IP network, can share a common block of extensions
designated in a gateway group.
1) Extn. 105 dialed
PBX A in Office A
Extn. 101
Extn. 103
Extn. 104
Explanation:
In the same way as when connected by a TIE Line, if a dialed number is not found at the local PBX, the call
can be sent to other PBXs connected via an IP network. When an extension number is dialed, the PBX first
searches local extensions for a matching number. If there is no match, the PBX then checks the TIE Line
Document Version 2016-03
15.1.23 Private Network Features—VoIP (Voice over Internet Protocol)
Leading Number
Dials "123XXX"
List
1. 1xx: GW Group-1
2. 2xx: GW Group-2
PBX-1
Private IP
V-IPGW
Network
Private IP
Network
V-IPGW
4) Check next PBX in
Gateway Group settings
Office A (GW Group-1)
PBX-2
V-IPGW(1)
Busy
V-IPGW(2)
Office B (GW Group-2)
Rerouted
PBX-3
V-IPGW(3)
V-IPGW(4)
2) Extn. 105 not
found in PBX B
V-IPGW
3) Rerouted
PBX C in Office C
V-IPGW
5) Extn. 105
found in PBX C
PBX B in Office B
Extn. 102
Extn. 202
Extn. 203
Extn. 105
Extn. 201
Extn. 303
Feature Manual 319