# NetworkInterface.T1E1[x].ISDN.D_Channel_Backup_Trunk

Specifies the 0-based trunk to carry the backup D channel for this NFAS group.

#### Syntax

NetworkInterface.T1E1[x].ISDN.D_Channel_Backup_Trunk = trunk

x = 0-(n-1) (0-based trunk number or range of trunk numbers where n equals the number of trunks on the board.)

#### Access

Read/Write

#### Type

Integer

#### Default

-1 (no backup D channel)

#### Allowed values

-1 to 3

#### Example

NetworkInterface.T1E1[0].ISDN.D_Channel_Backup_Trunk = 2

This example specifies that the backup trunk for T1E1[0] is trunk 2.

#### Details

The specified trunk must be a different trunk on the same board as the primary D channel interface and must be part of the same NFAS group.

When using this keyword, NetworkInterface.T1E1[x].D_Channel must be set to ISDN for the trunk (x) bearing the primary D channel.

#### See also

NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].Board, NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].NAI, NetworkInterface.T1E1[x].ISDN.NFAS_Member[y].Trunk, NetworkInterface.T1E1[x].ISDN.NFASGroup