The fast server interchange process is available only for the devices connected to the Processor Ethernet on duplicated servers. The branch gateways and IP telephones must have the updated firmware. The active server preserves information about all the connections and connects to IP telephones and branch gateways before resuming normal operation. The IP telephones and branch gateways accept the incoming connection to replace the old connection.

In a scenario where some of the branch gateways and IP telephones are upgraded and others are not, the following statements are true:

• The upgraded branch gateways and telephones reconnect faster

• The other branch gateways and telephones take longer time to reconnect

• The other branch gateways and telephones may negatively impact the performance of the server following the server interchange