Multi-User Alerting is the ability to notify multiple users (up to 10 users/schedules on Lite and Basic plans, up to 50 on Standard and Enterprise plans) at once when an incident has been triggered within a service. Multi-User Alerting looks like this in an escalation policy, with multiple people and schedules listed for one escalation rule:


Single-User Alerting notifies one person or one on-call schedule when an incident is triggered. Single-User Alerting looks like this in an escalation policy, with one person or schedule listed for one escalation rule:

So when should you use one type of notification over the other?
 

Single-User Alerting

Single-User Alerting works best for:

Notifying one person at a time
If one person tends to be the main escalation point for an open incident, then you will want to use Single-User Alerting. Single-User Alerting works best when you have a clearly definable escalation path that would only notify one person at a time.

Allowing one person to focus on an issue
With Single-User Alerting, no more than 1 person would be automatically assigned to a triggered incident. So if you only want one person to focus on resolving an issue–without distracting other members on your team who may not be able to resolve the incident–then Single-User Alerting will work best for this.

Escalating an incident to a manager
If you need an incident to escalate to a manager, then you will want to set up that manager as a sole escalation rule. For example, if your manager is the one who triages incidents, then you can set up your manager as the first escalation rule so that they can immediately receive notifications when something goes wrong and reassign them to the appropriate person. Or, you can set up your manager as the 2nd, 3rd, 4th, etc. escalation rule so that they can take action when an incident has not been immediately addressed by other on-call staff.

Escalating incidents to the next person in less than 5 minutes
Single-User Alerting allows you to escalate incidents to the next on-call person/people/schedule(s) in less than 5 minutes. So if it is a critical issue that needs immediate attention without delay, then you can set up an escalation policy to escalate to the next on-call team member in 1, 2, 3, or 4 minutes. If you have multiple users on one escalation policy (as would be set up under Multi-User Alerting), you would need to have a minimum of 5 minutes in between escalation rules, which may not be ideal if you need incidents to escalate immediately to the next person. What is the minimum amount of time that you can have between escalations?
 

Multi-User Alerting

Multi-User Alerting works best for:

Alerting multiple responders at once
In the case where you have a critical or high severity incident, Multi-User Alerting works great to get people working on an incident faster. By notifying multiple people at once immediately when an incident is triggered, you allow PagerDuty to create an all-hands-on-deck type scenario so that incidents are taken care of faster and nothing falls through the cracks.

Shadowing
It’s important to get your new hire ramped up as fast as possible. Multi-User Alerting allows your new hire to be notified with a veteran member of your team to address and resolve incidents.

Keeping interested parties informed in real-time
Multi-User Alerting makes it possible for managers to stay in the loop when an incident has been triggered. For example, a user can be added to the first level of an escalation policy to know when an incident has been triggered, and to the second level of an escalation policy to know when an incident has been escalated.

Notifying multiple teams for incidents
Some incidents may require team work across multiple teams in your organization. Need to notify your Operations team and your Support team? You can use Multi-User Alerting to add someone from Operations and Support to the same level of an escalation policy.