In many cases, you will have a group of people on-call during business hours and a different group of people on-call off business hours, or different groups of people on-call at various times of the day.
To notify different users at the same time during various times of the day (or days of the week), then you will want to:
Create on-call schedules that reflect each person's on-call rotations
Add each of these schedules to the appropriate layer of an escalation policy
To demonstrate this, we'll use the following example:
George, Emily, and Jennifer are on-call during business hours 0800-1700 and should all be notified at the same time
Naomi, Liam, and Max are on-call outside of business hours 1700-0800 and should all be notified at the same time
On the weekends, both George and Naomi are on-call and should be notified at the same time.
The first step in setting this up is creating on-call schedules for each user reflecting each user's on-call rotations and times.
For example, below are George and Max's schedule. Notice that we restrict the on-call times to certain times of the week for each schedule. Max is only on-call between 1700-0800 on the weekdays:
George is only on-call between 0800-1700 on the weekdays and all day on the weekends:
Once we have created each user's on-call schedule, we can then add each schedule to an escalation policy.
In the screenshot below, we have added each user's schedule (6 in total) to the first layer of an escalation policy. This means that if an incident is triggered between 0800-1700, then George, Emily, and Jennifer will be assigned and notified at the same time, since they are the only users on-call within that escalation layer.
When an incident is triggered between 1700-0800, then Naomi, Liam, and Max will be assigned and notified at the same time, since they are the only users on-call within that escalation layer.
On the weekends, only George and Naomi will be assigned and notified at the same time, since they are the only ones on-call over the weekend in that escalation layer.
Notice that we have set up our escalation policy so that the same group of users are re-notified after 10 minutes if they've not ack'ed or resolved the incident. If the group does not respond 10 minutes after that, then the incident is escalated to their manager, Tony Wagner.