When a UNIStim endpoint detects a server failure, the UNIStim endpoint does the following:

In a geo-redundant model, the UNIStim endpoints try to fail over within the primary load balancing server first.

However, if the primary cluster has insufficient capacity to support the fail over or if the S1 does not respond, then in a geo-redundant model, the outage time is the sum of the outage time caused during the initial registration failure and the time required to register to the geo-redundant cluster. The outage time is usually short and may not be detected by an end user, unless the user tries to use the endpoint during the fail over.

Depending on factors such as network speed and Session Manager resiliency, the fail-over time for the endpoint to register to a Device Adapter node is typically five minutes or less in addition to the time required to detect the geo-redundancy failure.

However, even a short interval for detecting the registration failure and failing over may be noticed by the users. Hence, even a very fast switch-over may be noticed by the users.