I use iLert for my agency to manage on-call and inform customers about issues. The initial setup took me a few hours, because we're using different monitoring tools and a ticketing tool for customers requests. Now all critical alerts and tickets go through iLert.

I love it how status pages are neatly integrated with my monitoring tools and uptime checks, so can I manage alerts and communicate incidents from a single application.

Their mobile app is great, too. It lets me change escalation policies, add overrides to on-call schedules and change notification channels.

And their on-call scheduling is super advanced. We use recurring schedules. Once setup, the on-call calendar will be generated automatically.