I feel like the core product is pretty easily replicated with Freeswitch and tailored with a little configuration. Eg: Ring a phone for 30 seconds (so as not to leave a message accidentally), if answered read back the issue (using text to speech), otherwise send the phone a text and <insert whatever else you want to do>.

Having set systems like this up for numerous clients, the latter bit is usually a case of waiting a few minutes for the on call person to either accept the alert, or failing that move onto whoever the fallback is for that person.

The core feature of Pagerduty here is resilience imo. As in, i expect whatever’s issue I’m having that they will not be having. I imagine if an AWS zone is down, large scale network issue, etc, any home rolled solution is likely to be impacted too.

While I get the point, two servers running Freeswitch combined with a bit of python and a regular rsyncing of the user data would give one pretty good uptime for monitoring.