Customer service window
Learn how the 24-hour customer service window works and the difference between session and template messages.
WhatsApp enforces a 24-hour customer service window to prevent spam and encourage quick support replies. The type of message you can send depends on whether this window is currently open or closed.
When this matters
Understanding the customer service window is crucial when:
- Designing automated chatbots or interactive support flows.
- Sending transactional alerts, OTPs, or marketing notifications.
- Handling agent-led customer service conversations.
Key rules
| Message Type | Session (Free-form) | Template |
|---|---|---|
| Trigger | Opened when a user sends an inbound message to your number. | Sent at any time, including when the window is closed. |
| Duration | Valid for 24 hours from the last user message. | No expiration. |
| Content | Any supported format (text, media, buttons, lists) with free-form text. | Pre-approved templates only. Must use defined variables. |
| Cost | Typically billed as user-initiated conversations. | Typically billed as business-initiated conversations. |
How the window works
When a customer sends a message to your WhatsApp Business number, it opens the customer service window.
- Active Session (Within 24 Hours): Your business can send free-form messages (session messages) to the user. Each time the user replies, the 24-hour timer resets.
- Expired Session (After 24 Hours): Once 24 hours have passed since the user’s last message, the window closes. You can no longer send free-form messages. To resume messaging, you must send an approved template message.