Every week we test PagerDuty to make sure it can phone to alert us to any issues.
Cron creates a file on disk. Icinga raises a critical alert when that file exists with an Icinga contact group set so that PagerDuty is notified. After a short amount of time, cron will remove the file to resolve the alert. The code that does this is in Puppet.
You don’t need to take any action for this alert. The primary in-office 2nd line should escalate the call to the secondary who should escalate it to “escalations” to ensure that phone redirection is working. The person on “escalations” will resolve the PagerDuty alert to prevent anyone else being phoned.