We have built Pagerly which updates the Slack user group (like @sre-oncall) with your Oncall schedule and your current oncall.
You can also receieve
Instant Notification on Oncall Rotation/Handover
Start tagging oncall like @dev-on-call,
Have Automated Response for Each Oncall Mention To Free Developer Time
In short one can Manage Rotations, override, notify, and engage oncalls via Slack