Configuring ISDN ports settings

Whether this port may be used to make and receive ISDN calls.

Specify the number of digits that a caller will dial before the ISDN gateway will apply the dial plan and make the IP part of the call.

When the ISDN gateway has received that number of dialed digits, it will connect the call immediately.

If you do not want to use overlap receiving, enter 0 to disable this feature.

Overlap receiving ensures that the ISDN gateway waits for all dialed digits before connecting the call. To use overlap receiving, it must be supported by your ISDN infrastructure.

When overlap receiving is enabled, the ISDN gateway can collect a series of dialed digits sent from an endpoint before it starts the IP leg of the call. Overlap receiving is configured on an individual PRI port basis.

Note that this setting is not available when the ISDN gateway is operating in leased line mode.

The directory number of this ISDN port.

Enter the phone number of this port, as assigned by your ISDN network provider. In many applications, all ISDN ports will share a common directory number; this is referred to as the ports being part of a hunt group. Incoming calls may arrive at any one of the ports with a shared directory number.

Note that when receiving an incoming ISDN call, the gateway advertises the directory numbers of the ports selected in the dial plan. If no directory number is specified, it assumes the directory number of the nearest lower-numbered port. If no ports have a specified directory number, the calling endpoint will be instructed to use the same number to place subsequent calls as it used to make the first call.

The national prefix that the ISDN gateway adds.

This setting adds a prefix to the calling party number information which the ISDN gateway gets from an incoming ISDN call and then sends out over the IP part of the call.

This calling party number can then be used by an IP participant to return a call to the ISDN participant.

This feature should be used in conjunction with the overall dial plan mechanism.

The international prefix that the ISDN gateway adds.

This setting adds a prefix to the calling party number information which the ISDN gateway gets from an incoming ISDN call and then sends out over the IP part of the call.

This calling party number can then be used by an IP participant to return a call to the ISDN participant.

This feature should be used in conjunction with the overall dial plan mechanism.

The lowest numbered B-channel available.

An ISDN PRI comprises a number of B-channels. A complete PRI has 30 available B-channels when using E1, and 23 when using T1 or J1. Your ISDN network provider may offer a complete or fractional PRI (where a reduced number of B-channels are available). In either case, the low channel number is generally 1.

Refer to your ISDN network provider if you are unsure of which value to use here.

The highest numbered B-channel available or Max.

An ISDN PRI comprises a number of B-channels. A complete PRI has 30 available B-channels when using E1, and 23 when using T1 or J1. Your ISDN network provider may offer a complete or fractional PRI (where a reduced number of B-channels are available).

Use Max if you are unsure of which value to use here or refer to your ISDN network provider. Also use Max if you may switch between E1 and T1/J1 modes.

Select whether free B-channels should be selected starting with the low-numbered channel and working towards the high-numbered channel, or the other way around.

When making outgoing ISDN calls, the ISDN gateway requests that the ISDN network makes the call using a particular set of B-channels; when receiving incoming ISDN calls, the ISDN network informs the ISDN gateway which B-channels are in use.

To minimize the risk of a new incoming call using the same B-channels as a new outgoing call starting at the same time, you should generally set the ISDN gateway to search free channels in the reverse order to the ISDN network.

Refer to your ISDN network provider if you are unsure of which value to use here.

Select to enable Non-Facility Associated Signaling (NFAS).

This setting is only visible when the ISDN gateway is configured to use T1 as the ISDN interface type. To configure the ISDN interface type, go to Settings > ISDN.

NFAS allows multiple PRIs (in T1 mode) to use a single D-channel. The NFAS settings on the ISDN gateway must match the settings on the ISDN switch to which the ISDN gateway is connected.

Select an ID for the NFAS group.

Allocate the same NFAS group ID to each port that will use the same D-channel. Ports with the same NFAS group ID are in the same NFAS group.

Select an ID for the NFAS interface.

Within the NFAS group, each NFAS interface ID must be unique, must be between 0 and 31, and must be the same as that set on the switch to which the ISDN GW is connected.

Select the D-channel type.

Within the NFAS group, one port must have the D-channel type set to Primary (active) and the other ports must have D-channel type set to None. This must match the settings on the switch.