# WhatsApp

> The same brain on WhatsApp: free-form replies inside Meta's 24-hour session window, approved templates outside it, quiet hours, and the missed call → WhatsApp play.

The WhatsApp service answers the business's WhatsApp number with the same agent, knowledge, and flows as every other door. It also carries outbound: workflow notifications and [campaigns](/docs/campaigns/overview) can message customers on WhatsApp — with Meta's rules handled for you.

## The 24-hour session window

Meta allows free-form messages only within 24 hours of the customer's last message. OpenAgent applies the rule automatically wherever a WhatsApp message is sent:

| Situation | What OpenAgent sends |
| --- | --- |
| Customer wrote within the last 24h | A normal **session message** — free-form text, written by the AI or your workflow |
| Window closed (or first contact) | An **approved template** — you pick which template the workflow or campaign uses |

Templates are created and submitted for Meta approval from the service's **Templates** page; approved ones become selectable in [workflow notifications](/docs/workflows/notifications) and campaigns.

## The missed call → WhatsApp play

A favorite for med spas and trades: trigger *A call goes unanswered* → notification → WhatsApp. Inside the window the AI texts free-form and finishes the booking in-thread; outside it, the approved "sorry we missed you" template opens the conversation and the AI takes over on the reply. Build it in [Recipes](/docs/workflows/recipes).

## Quiet hours & suppression

- **Quiet hours** hold outbound sends until a decent hour — the 2am blast nobody meant to send stays unsent.
- **Missed-call texts are queued and swept**, not fired by fragile timers — a held message goes out when quiet hours end.
- **STOP and DND** anywhere stop everything: one suppression list covers the whole workspace. See [DND & suppression](/docs/crm/dnd).