The notification system is also an extensible and flexible system.
So e.g. in shift operation in different working times different notification mechanisms can be left. These mechanisms are customizable in kind of notification (E-Mail, SMS or the like), frequency, period of time and escalation steps. At first, in case of failure the responsible employee is informed about the fault. This happens in a defined time period in specified frequency. If the employee does not react or acknowledged the fault in the Nagios system more escalation steps are informed according to a defined frequency, before. This could be a chief executive. This thread can be continued till an external service provider is informed.