Howto Hardware Bridging with berofix

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Howto Hardware Bridging with berofix

This Howto will describe you howto enable Hardware bridging on a berofix card. Hardware Bridging (HW-Bridging) means that you transmit the voicestream (in digital environments the B-Channels data) between two PSTN Ports transparently in Hardware via TDM (TDM TimeDivisionMultiplex), without any delay and loss of data. HW-Bridging makes sure that sensible services like FAX , Modem or ISDN data services work like expected. You can establish HW-Bridging on one LineInterface, between two LineInterfaces on one berofix card or even between berofix cards through the pcm bus.

The berofix card will enable HW-Bridging if the berofix gets an SIP Re-Invite on his self. This sounds complicated but it isn't. Lets have a look to schema 1: You got a call from PSTN on Port1 and want to bridge this call to Port 2 where a Fax is located.

  • 1. You got an inbound call on Port 1 from PSTN.
  • 2. You got a match in the berofix Dialplan and routed this call to the SIP Server.
  • 3. The SIP Server detect this call and route it back to the berofix card.
  • 4. The berofix gets a SIP-Reinvite and activate HW BRidging
  • 5. berofix routes the Call to the Fax on Port 2.


Bf bridging schema.png
schema 1:

After this HW Bridging is active. As you can see SIP-ReInvites are necessary to activate it, so please take care about this. The szenario to activate HW Bridging is always like described before. If you want to activate HW-Bridging between 2 LineInterfaces you have to set the master /slave Option on the WebGUI under the section Hardware. If one LineInterface is set to Master and the other one is slave HW Bridging will be activated between both modules. If both are set to master HW Bridging will be deactivated between the modules.

Note for Asterisk: When you use Asterisk and use "canreinvite=yes" you must not provide the "t" or "T" Options in app_dial. These prevent Asterisk to send re-Invites.