You can guarantee that when the system is down, at the exact same time a user or employee they has an urgent piece of work to complete or a proposal that need to be sent NOW!
Would you prefer your response to be:
a) We’ll get right on it.
b) We are already looking into it.
Proactive monitoring is not your client or colleague calling to tell you they cannot access email or a file or the web server.
Have a look at you proactive alerting and monitoring systems and ask yourself if they are checking that the service is available to the end user or is it simply a number of standard checks?