Triggered downtime in a Maintenance Window

Often, telcom/isps provide a maintenance window indicating your connection will be down for x amount of time within that window.  With those windows typically being large chunks of time, it would help to be able to set a triggered down time instead of setting down time for the whole maintenance window.  I.E. you set the downtime window for 6 hours and the actual downtime for an hour.  Once the connection goes down within that window, the actual downtime is triggered and is set for the next hour.