How to set up an on-call rotation in Slack

Give your team one handle, such as @dev-on-call, that points to the person currently responsible. Ternly changes that Slack user group’s membership as the rotation moves from one teammate to the next.

Before you start

You need a paid Slack workspace and an installer with permission to manage user groups, usually a workspace administrator. Use a dedicated group: activating a rotation replaces its existing membership. Ternly’s trial and planned subscription are separate from your Slack plan.

1. Connect your workspace

Add Ternly to Slack, review the permissions, and choose your workspace. Open Ternly’s Home tab in Slack and choose New rotation.

2. Give the rotation a handle

Name the rotation, then select a dedicated Slack user group or create one inside the form. For example, use dev-on-call for engineering or support-on-call for support duty. If you want handoff announcements, select a public channel and invite Ternly into it.

3. Choose people and the handoff time

Select teammates in the order they will take turns. Choose an interval of 1–90 calendar days, an IANA timezone such as America/Vancouver, and the first handoff date and time. Daily means a handoff each day at your chosen local time; a weekly rotation uses seven calendar days.

A 09:00 handoff means the previous person is still responsible at 08:59. The schedule follows that local clock through daylight saving changes. This version runs continuously; it does not skip weekends or apply business-hours restrictions.

4. Preview before activating

Review the upcoming people and times, the group whose members will change, and the announcement channel. Save when they are correct. A future rotation leaves the group unchanged until it starts. The scheduler runs about once a minute; check for a confirmed Slack update rather than assuming a saved form is already synchronized.

5. Mention the group or look up the owner

In a Slack message, type @dev-on-call and select the real user group from Slack’s mention picker. Slack addresses the group’s current members. Notification delivery still follows Slack’s permissions, channel access and notification settings.

Use /ternly for a private overview, or /ternly dev-on-call for that group. The /oncall alias also works. A group mention and a slash command serve different jobs: contacting the person and checking who is responsible.

Handle time off without changing the whole rotation

Choose Arrange cover in Slack or on the web. Select the person and a finite window, then review who takes over and who resumes. Administrators can assign cover; participants can volunteer themselves. The underlying rotation continues during coverage, and overlapping overrides are rejected.

Verify your first handoff

Open the user group in Slack and confirm its member matches Ternly’s current owner.
Check the last confirmed sync time and the optional channel announcement.
With two teammates, verify the next scheduled handoff and a temporary cover/resumption.

If a group update fails, check the installer’s group-management permission. If an announcement fails, invite Ternly to the selected public channel. See troubleshooting and support for recovery steps.

Know the boundaries

Ternly manages a single primary person per rotation. It does not provide emergency paging, escalation, multiple simultaneous owners, calendar feeds or personal reminders. Pause stops future updates and leaves Slack membership in place; removing a rotation also keeps the group. It does not automatically become empty when paused.

Slack’s user-group documentation explains workspace permissions and mentions. For the working product, try the browser-local demo or install Ternly’s no-card trial.