CHAPTER 25 Routing
Parameter
'Release Cause'
rel-cause
[AltRouteCauseIP2Tel_
ReleaseCause]
Alternative Routing to an IP Destination upon a Busy Trunk
The Forward on Busy Trunk Destination table lets you configure alternative routing rules for
forwarding (i.e., call redirection) IP-to-Tel calls to an alternative IP destination using SIP 3xx
responses. The alternative routing is triggered upon the following:
■
Digital interfaces: Trunk Group has no free channels (i.e., "busy").
■
Analog interfaces: Unavailable FXS / FXO Trunk Group. This feature can be used, for
example, to forward the call to another FXS / FXO.
This feature is configured per Trunk Group. The alternative destination can be defined as a host
name or as a SIP Request-URI user name and host part (i.e., user@host). For example, the below
configuration forwards IP-to-Tel calls to destination user "112" at host IP address 10.13.4.12, port
5060, using transport protocol TCP, if Trunk Group ID 2 is unavailable:
ForwardOnBusyTrunkDest 1 = 2, 112@10.13.4.12:5060;transport=tcp;
When configured with user@host, the original destination number is replaced by the user part.
The device forwards calls using this table only if no alternative IP-to-Tel routing rule has been
configured in the IP-to-Tel Routing table or alternative routing fails and the following reason(s) in the
SIP Diversion header of 3xx messages exists:
■
Digital interfaces: "out-of-service" - all trunks are unavailable/disconnected
■
"unavailable":
●
Digital interfaces: All trunks are busy or unavailable
●
Analog interfaces: All FXS / FXO lines pertaining to a Trunk Group are busy or unavailable
The following procedure describes how to configure Forward on Busy Trunks through the Web
interface. You can also configure it through ini file [ForwardOnBusyTrunkDest] or CLI (configure
voip > gateway routing fwd-on-bsy-trk-dst).
➢
To configure a Forward on Busy Trunk Destination rule:
1.
Open the Forward on Busy Trunk Destination table (Setup menu > Signaling & Media tab >
Gateway folder > Routing > Forward on Busy Trunk Destination).
2.
Click New; the following dialog box appears:
Defines a Q.931 release code that if received, the device attempts
to route the call to an alternative destination (if configured).
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Mediant 800 Gateway & E-SBC | User's Manual
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