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In an HA system, each phone chooses either the Primary or some Secondary system with which to register. The load sharing distribution by default is evenly distributed across all SIP Router systems, but can be changed by configuring the DNS server. As soon as a phone registers with any server, sipXecs replicates this registration data to all other SIP Routers. Using the management Web UI you can see what phones used which server (which helps you measure whether your DNS is set up correctly and whether the phones can connect to the servers equally). The example below shows three phones, a Polycom, Snom and Grandstream, where two use the Master as their primary registrar and one used the Slave.
