Who handles it? The DevOps Team
Normally, one single on-call person will acknowledge and initially respond to an incident. But, the on-call engineer may not always be the person with the knowledge to start fixing the problem. So, establishing a DevOps-based incident management solution will focus on the ability to route, escalate, and collaborate around issues. The on-call engineer can easily pull in teammates who need to be involved and prioritize the incident response quickly and easily.
The next level of incident response will add context to an alert when the on-call engineer receives it. That way, they can quickly and easily diagnose the problem, assess who needs to be involved, and escalate the issue appropriately. Being notified of a system alert with no context is only slightly better than not receiving an alert at all.
A DevOps team, with the proper tools and processes, can acknowledge an issue, re-route the problem based on contextual alerts, loop in the necessary people, and collaborate around the problem all in one place.