Connecting your PBX to a Far South Networks ISDN gateway

In some instances, you may require Basic Rate MISDN ports on your PBX system. These ports are rather antiquated now, and seldom feature in new installations. However, in some cases, a customer may have existing BRI infrastructure that they wish to maintain, whilst also wanting to take advantage of unified communications , or the cost reducing practice of "bring your own device".

For such scenarios, we recommend the use of a Far South Networks BRI gateway, to sit in-between the 3CX PBX, and the legacy BRI service provider.

The gateway will connect to the service provider via BRI, and to the FSN 3CX PBX Appliance through a SIP trunk .

Calls received on the BRI ports, are passed directly to the PBX over the SIP trunk, whilst calls received on the SIP trunk are sent out over the BRI trunks to the service provider.

PBX Configuration

On the PBX, you need only create a SIP trunk between the PBX and the gateway, and then create a outbound and inbound routes to process the DIDs according to your needs.

The SIP trunk should be configured to identify by IP address only, rather being account based.

Gateway Configuration

The gateway configuration comprises two flexpaths and two outbound routes., and two trunks.

The first step is to configure a trunk between your gateway and the FSN 3CX PBX Appliance.

The simplest way to configure this would be to create a SIP trunk on both the gateway and the FSN 3CX PBX Appliance, and have the SIP trunk identify using IP addresses, and no authentication.

On the gateway, create a new SIP trunk.

Set the trunk to neither act as the provider, nor register with the provider. Enter the IP address of the FSN 3CX PBX Appliance as the SIP provider.

This will create a trunk that identifies by IP address only.

The create an outbound route that routes all calls to the PBX over this gateway trunk.

Then, make sure that all BRI ports are in a trunk group, and make a second outbound route that also routes all calls, but over the ISDN trunk group.

Once the outbound routes have been created, create a flexpath for each route.
Generally, I create a flexpath named "From-Provider" and another named "From-PBX".
In the flexpath called "From-Provider", I add an include route, which includes the outbound route that sends calls to the PBX. This way, calls that come from the service provider, and sent to the PBX.

Then, in the flexpath named "From-PBX", I include the outbound route that sends calls to the service provider. In this manner. Calls from the PBX are sent to the service provider.

Finally, in the ports tree, make sure that the configured SIP trunk is a member of the "From-PBX" flexpath, and that the BRI trunk group is a member of the "From-Provider" flexpath.