The 24-hour window is the period that opens every time a customer messages or calls you on WhatsApp. Meta calls it the customer service window. While it is open, your business can reply with free-form messages, and every new message from the customer restarts it. Once it closes, you can only write to them with an approved template.
In practice
The rule applies to the WhatsApp Business API. According to Meta's documentation, inside the window you can send "service messages" with no prior approval: text, images, documents, locations, option lists, up to three reply buttons or a WhatsApp Flows form. Outside it, the only route is a WhatsApp message template, reviewed by Meta and sent to someone who has given their prior opt-in.
An example: an owner reports a leak on Friday at 18:00. If the property manager replies on Saturday at 10:00, they can write free text. If they reply on Monday, the window has closed and they need a utility template, such as an update on the repair request.
The window also affects cost. As of October 2026, Meta gives 1,000 free service messages a month per number and charges for the rest; in Spain, €0.0166 each. Since 1 October 2026 it has also charged for utility templates sent inside the window (Meta pricing).
There is a variant: if the customer messages you from a click-to-WhatsApp ad, using the Android or iOS app, and you reply inside the window, a "free entry point window" opens that can last up to 7 days. While it lasts, Meta does not charge for marketing, utility, authentication or service messages; messages from its own agent, Meta Business Agent, are still charged.
For a chatbot or an AI agent, this means knowing at every moment whether the window is open. We explain it in how to build a WhatsApp AI agent and in WhatsApp Business API pricing in Spain.
Common mistakes
- Replying with free text after it has closed. The send fails. The system has to pick the right template or send nothing.
- A team that takes more than a day. If the handover to a person comes too late, the conversation can only be picked up again with a template.
- Splitting each reply into several messages. Each one counts as a service message, and Meta only allows one message every 6 seconds to the same user on a sustained basis.
- Mistaking the window for permission. A customer writing to you does not entitle you to send them promotions once the window closes: templates need their consent.
Sources
- Meta, Service messages and the customer service window
- Meta, Pricing on the WhatsApp Business Platform (updated 30 September 2026)
- Meta, Template fundamentals
- Meta, Get opt-in for WhatsApp
- Meta, About the WhatsApp Business Platform