3Com VCX V7122 SIP, User Manual

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3Com VCX V7122/SIP VoIP Gateway User Manual
Trunk to Trunk Routing Example
This example describes two VCX V7122 Gateways, each interface with the PSTN through
four E1 spans. Gateway A is configured to route all incoming Tel
Æ IP calls to Gateway B.
Gateway B generates calls to PSTN on the same E1 Trunk as the call was originally
received (in Gateway A).
Gateway A IP address is 192.168.3.50.
Gateway B IP address is 192.168.3.51.
To define the INI file parameters of Gateways A and B, follow these steps:
1
Define, for both Gateways, four trunk groups; each with 30 B-channels:
TrunkGroup_1 = 0/1-31,1000
TrunkGroup_2 = 1/1-31,2000
TrunkGroup_3 = 2/1-31,3000
TrunkGroup_4 = 3/1-31,4000
2
In Gateway A, add the originating Trunk Group ID, as a prefix, to the destination number,
for Tel
Æ IP calls:
AddTrunkGroupAsPrefix=1
3
In Gateway A, route all incoming PSTN calls, starting with the prefixes 1, 2, 3, and 4, to
Gateway’s B IP address:
Prefix = 1, 192.168.3.51
Prefix = 2, 192.168.3.51
Prefix = 3, 192.168.3.51
Prefix = 4, 192.168.3.51
It is also possible to define Prefix = *,192.168.3.51 instead of these four lines.
4
In Gateway B, route IP Æ PSTN calls to Trunk Group ID according to the first digit of the
called number:
PSTNPrefix = 1,1
PSTNPrefix = 2,2
PSTNPrefix = 3,4
PSTNPrefix = 4,4
5
In Gateway B, remove the first digit from each IP Æ PSTN number, before it is used in an
outgoing call:
NumberMapIP2Tel = *,1,none
SIP Call Flow Example
The Call Flow, shown in Figure 23 , describes SIP messages exchanged between VCX
V7122/SIP Gateway and an VCX V7111 8FXS Gateway during a simple call.
1
The VCX V7111 8FXS has the phone number 8000 and calls the VCX V7122 with the
phone number 1000: