Fault-Tolerant Office VoIP Telephone Network - SIP through SpeedFusion with Failover to Landline


  • This shop has two branches, with a centralized 3CX VoIP PBX at head office and remote VoIP handsets at Site 1.
  • All calls come in over SIP from an external SIP provider and are handled and routed by the 3CX PBX server at the HQ site to handsets at both locations.


  • VoIP call resilience between locations. VoIP calls should not drop when a WAN link fails.
  • QOS to prioritise VoIP across the VPN between the remote site and the HQ site.
  • Load balanced bandwidth at all locations. Adding additional bandwidth (DSL/EFM/FTTC) to any location should be cheap and easy.

Recommended Solution:

  • Balance 380 at both locations allowing for up to 3 WAN links of any type all of which can provide load balanced internet access and be bonded into a SpeedFusion VPN tunnel.
  • SpeedFusion VPN between the two locations to provide an Unbreakable VPN to maintain live VoIP calls even if a WAN link should fail mid call.

Additional Benefits of this solution

  • Cellular dongles can be used on the Balance 380s to provide a 4G/LTE backup in the event all fixed line connectivity fails.
  • Multiple ISPs can be used for provider diversity.