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Redfone Communications has a very interesting product coming to market – a solid state, virtual plug-and-play "appliance" used in conjunction with Asterisk which can be used instead of Digium or Sangoma cards. In addition, using the Redfone foneBRIDGE you can create a redundant deployment of Asterisk. As seen by the diagram below, you can configure multiple Asterisk servers – none of which have any TDM (PRI/T1) hardware cards in them. Instead, you use the foneBRIDGE to terminate to PRI or T1 channel banks on the trunk side and Ethernet to connect to the Asterisk boxes.