WhatsApp 24-Hour Window

The 24-hour window (also called the *customer service window*) is the central rule of conversational messaging on WhatsApp: when a customer messages a company, a 24-hour period opens during which that company can reply with free-form messages (text, images, buttons, lists) without paying a template fee and without prior approval from Meta. The clock runs from the user's last message, not from the start of the conversation.

While the window is open, service flows like a normal chat. When it closes (24 hours have passed without the customer writing again), the company can no longer send free-form text: to resume contact, it needs to use a pre-approved WhatsApp template (HSM), which does have a cost. It is the mechanism Meta uses to separate user-initiated conversations (cheap, open) from business-initiated ones (controlled, template-based). That is why it is a key concept for any WhatsApp Business API integration and part of what gets governed when you connect WhatsApp to your CRM.

The 24-hour window exists because WhatsApp does not want to become an outbound spam channel the way SMS did. The underlying logic is simple: if the customer reached out to you, they showed interest, so you can reply freely; if you are the one who wants to start (or restart) the conversation, you have to go through an approved template. That asymmetry shapes the entire operational design of customer service and marketing on WhatsApp.

How the clock works in practice

Every incoming message from the user opens or restarts a 24-hour window. If a customer writes at 10:00 a.m. on Monday, the company can reply freely until 10:00 a.m. on Tuesday. If the customer writes again at 6:00 p.m. on Monday, the clock is recalculated from that moment: the window now runs until 6:00 p.m. on Tuesday. As long as there is ongoing back-and-forth, the window stays alive with no additional template cost.

The detail that confuses teams the most is this: the window is measured from the customer's last message, never the company's. Your reply does not extend anything. If the agent answers at 11:00 a.m. but the customer does not write again, the window still expires at 10:00 a.m. the next day.

What you can do inside and outside the window

• Inside the window (open): free-form messages, no template, no approval. This is the normal mode for an omnichannel inbox and human customer service.
• Outside the window (closed): only pre-approved HSM templates, billed according to the template category (utility, marketing or authentication).
• Reopening the conversation: you send a template; if the customer replies to it, a new 24-hour window opens and you can use free-form text again.

The service window and message pricing

The 24-hour window determines what type of message you can send; pricing runs on a separate track. Meta bills per delivered message: templates are charged by category and country, and free-form replies inside the window (service messages) include 1,000 free per number per month, after which they are paid at the utility rate. The previous model, per-conversation pricing, charged for the whole window once.

A concrete example (Argentina, LATAM)

An e-commerce company in Buenos Aires receives a question from a customer about the status of their order. The window opens: the agent, and then a chatbot, reply freely, share the tracking number and resolve the question. The customer is satisfied and does not write again. At hour 26, logistics confirms the package is out for delivery. Since the window has already closed, the company cannot send free-form text: it triggers a pre-approved utility template ("Your order is out for delivery") with a button. If the customer replies "thanks, what time will it arrive?", a new window opens and service flows again without a template. That back-and-forth between an open window and a template is the daily rhythm of any serious conversational commerce operation.

Common mistakes

• Believing that replying extends the window. It does not: only the customer's message restarts the clock.
• Letting the window lapse without resolving the issue. If the customer was left waiting and the 24 hours run out, picking the thread back up costs a template; it is better to resolve things while the window is open.
• Using marketing templates as if they were free-form text. Spamming with templates lowers your WhatsApp quality rating and can degrade the number.
• Not automating window tracking. Without a CRM that knows whether the window is open or closed, agents try to send free-form text too late and the message fails.

Understanding the 24-hour window well is what separates a clean WhatsApp operation (fast, inexpensive, with a good rating) from one that burns budget on templates and annoys its customers.