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.
On unofficial channels, the 24-hour customer service window is not technically enforced by Meta, but adhering to it is highly recommended to protect your number from being blocked for spam.