The time during which a system is unavailable; the most basic measure for accessibility. Go inbound telephone systems are expected to be operational 99,999 percent of the time, which is commonly referred to as 'five nines'.
System downtime affects the contact center performance to a serious extent. This may be a reason to include downtime as a KPI in the periodic reporting contact center. Another solution to prevent problems resulting from downtime is to make systems redundant. When one system fails, the other system takes over.
See Key Performance Indicator, redundancy