This is the timestamp of when the node recorded its highest number of simultaneous calls in place since the last statistics reset. It lets an admin tie a call-capacity peak to a specific moment, which is useful when the node's call-handling limit is being approached and you need to know whether it happened during a predictable busy hour or an unexpected event. For example, if this shows a timestamp during a Monday-morning login rush, that corroborates a capacity-planning theory about peak office hours.