How the Conversation Window Works
WhatsApp uses a 24-hour conversation window to control when businesses can send free-form messages. The window opens when a customer messages you, and it lasts for 24 hours from the customer's last message.
What Opens the Window
A customer sends you a message (text, image, button reply, etc.)
A customer taps a call-to-action button in a previous message
A customer replies to a template message
Each new message from the customer resets the 24-hour timer.
During the Window (Open)
While the window is open, you can send:
Free-form messages (text, media, location, contacts, interactive)
Template messages (these still work within the window)
Free-form messages within the window create Service conversations, which are typically the lowest-cost conversation category.
After the Window Closes (Expired)
Once 24 hours have passed since the customer's last message:
Free-form messages will fail
You must use an approved template message to re-initiate contact
The template message opens a new conversation (billed at the template's category rate)
Conversation Billing
Each conversation is billed once when it opens. The conversation type determines the rate:
Conversation Type | How It Opens | Duration |
Service | Customer messages you, you reply with free-form | 24 hours from window open |
Marketing | You send a Marketing template | 24 hours from template send |
Utility | You send a Utility template | 24 hours from template send |
Authentication | You send an Authentication template | 24 hours from template send |
Tips
Respond promptly — The 24-hour window starts from the customer's message, not your reply. Delays eat into your free-form messaging time.
Use templates strategically — If you need to follow up after the window closes, have relevant templates pre-approved and ready.
Monitor via webhooks — Use delivery status webhooks to track whether messages succeeded or failed due to window expiration.