Alternative Routing to an IP Destination upon a Busy Trunk

The Forward on Busy Trunk Destination table lets you configure up to 100 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:

■

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 calls to another FXS / FXO endpoint.

The feature is not applicable to Trunk Groups whose 'Channel Select Mode' parameter is configured to By Dest Phone Number, Dest Number & Cyclic Ascending, or By Dest Number & Ascending in the Trunk Group Settings table (see Configuring Trunk Group Settings).

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:

Open the Forward on Busy Trunk Destination table (Setup menu > Signaling & Media tab > Gateway folder > Routing > Forward on Busy Trunk Destination).

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.

Configure a rule according to the parameters described in the table below.

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.