Scenario 3: Multi-Site - No Legacy PBX
This configuration shows a head office with a mix of hardware and software IP phones communicating via the Internet to one or more branch offices. All communication between the offices is free (even if they are located in another country). Legacy analogue phones at any site can be connected via ATAs or an FXS gateway.
Remote home workers have extensions that work in the same way as those of their branch and head office peers. They can receive transferred or redirected calls, be incorporated into hunt groups and included in conference calls; and all communication with them is free.
Organisations adopting this configuration would typically consolidate their voice and data traffic through bonded ADSL, SDSL or E-carrier lines. This configuration provides easy scalability to add new extensions; redundancy should a given ISP go down; QoS routing of voice traffic; and load balancing across links.