Panasonic KX-TDE100 Feature Manual page 267

[Example]
Gateway Settings List
1. IP-GW(1): GW Group-1
2. IP-GW(2): GW Group-1
3. IP-GW(3): GW Group-2
4. IP-GW(4): GW Group-2
When "123XXX" is dialed, the call is routed to GW Group-1. However the lowest-numbered device (IP-GW(1))
is busy or not available, so the call is rerouted to IP-GW(2).
Note
For information about assigning groups when using the IP-GW card, refer to the Programming Guide of
the VoIP Gateway Card.
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) Ext. 105 dialed
PBX A in Office A
Ext. 101
Ext. 103
Ext. 104
Explanation:
Document Version 2009-12
13.1.25 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
IP-GW(1)
Busy
IP-GW(2)
Office B (GW Group-2)
Rerouted
PBX-3
IP-GW(3)
IP-GW(4)
2) Ext. 105 not
found in PBX B
V-IPGW
3) Rerouted
PBX C in Office C
V-IPGW
5) Ext. 105
found in PBX C
PBX B in Office B
Ext. 102
Ext. 202
Ext. 203
Ext. 105
Ext. 201
Ext. 303
Feature Manual 267