PBX to PBX
A single PBX can handle many extensions and connections. The only limiting factor is the total bandwidth used to connect the extensions to the PBX.
To allow a more diverse VOIP system, groups of extensions are connected to their own PBX, eg all extensions within the 0191 area, all extensions within the 01642 area.
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If extension 0191ext1 wants to talk to extension 01642ext2, the direct dial number would be 01642ext1 and within the NEDNET-PBX, the OUTBOUND ROUTE dial pattern knows to route the call to NEDNET-PBX1.
As the system expands, more PBX's would be utilised to cover a specific AreaCode and located within the mesh area.