Alternative Routing to an IP Destination upon a Busy Trunk

The Forward on Busy Trunk Destination table lets you configure up to 288 alternative routing rules for forwarding (i.e., call redirection) IP-to-Tel calls to an alternative IP destination (instead of the Tel destination) using SIP 3xx responses. The alternative routing is triggered upon the following:

Unavailable FXS Trunk Group. This feature can be used, for example, to forward calls to another FXS endpoint.

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:

"unavailable":
All FXS 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:

The figure above displays a configuration that forwards IP-to-Tel calls destined for Trunk Group ID 1 to destination IP address 10.13.5.67 if conditions mentioned earlier exist.

3. Configure a rule according to the parameters described in the table below.
4. Click Apply, and then restart the device with a save-to-flash for your settings to take effect.

Forward on Busy Trunk Destination Parameter Descriptions

Parameter

Description

'Index'

[Index]

Defines an index number for the new table row.

Note: Each row must be configured with a unique index.

'Trunk Group ID'

trunk-group-id

[TrunkGroupId]

Defines the Trunk Group ID to where the IP call is destined.

'Forward Destination'

forward-dst

[ForwardDestination]

Defines the alternative IP destination for the call used if the Trunk Group is busy or unavailable.

The valid value can be an IP address in dotted-decimal notation, an FQDN, or a SIP Request-URI user name and host part (i.e., user@host). The following syntax can also be used: host:port;transport=xxx (i.e., IP address, port and transport type).

Note:

If you do not specify a port, the device uses UDP port 5060.
When configured with a user@host, the original destination number is replaced by the user part.