WhatsApp 24-Hour Customer Service Window: How It Works
Short answer
When a customer messages your WhatsApp Business API number, a 24-hour customer service window opens. Inside it you can send free-form replies. Each new customer message resets the 24 hours. After it closes, you can only send pre-approved template messages until the customer writes again.
The 24-hour window is the single most important rule to understand when you run WhatsApp support on the Business API. It shapes how fast you need to reply, which messages you can send, and what your WhatsApp costs look like. Here is how it works in practice.
What the window is
WhatsApp treats customer-initiated and business-initiated conversations differently. When a customer sends you a message, WhatsApp opens a customer service window that lasts 24 hours from their most recent message. While it is open, you can reply with free text, images, documents and other rich content, with no template needed.
Every time the customer writes again, the 24 hours restart. A long, active conversation can therefore stay open indefinitely. A one-off question that you do not answer promptly may leave you with a window that closes before you finish helping.
What you can and cannot send
| Situation | What you can send |
|---|---|
| Window open (customer wrote in the last 24 hours) | Free-form messages: text, media, interactive content |
| Window closed | Only approved message templates |
| You want to message someone who has never contacted you | Only approved templates, and only to contacts who have opted in |
Templates must be approved by Meta before use and fall into categories such as utility and marketing. See our message templates guide for how approval works.
Why it matters for support teams
- Reply speed becomes a compliance and cost issue, not just a service-quality one. A conversation that slips past 24 hours needs a template to reopen.
- Handovers can break the window. If a chat sits unassigned overnight, the customer may be outside the window by the time an agent picks it up.
- Follow-ups need planning. Anything you want to send after the window closes has to be a pre-approved template.
How to stay inside the window
- Route messages the moment they arrive. Use auto-routing and assignment rules so nothing waits in an unowned queue.
- Use an out-of-hours reply. An automatic message tells the customer when to expect an answer without you having to be online.
- Let an AI agent handle first responses. A WhatsApp AI agent can answer routine questions immediately and hand complex ones to a human, keeping conversations active.
- Set SLA alerts. Flag conversations that are approaching the end of their window so an agent can follow up in time.
- Ask the customer to reply. A closing line like “Reply here if that didn’t solve it” invites a message that reopens the window.
What to do when the window has closed
You have two options: wait for the customer to write again, or send an approved template that invites them to continue the conversation. If you take the template route, make sure the customer has opted in to hear from you and that the template’s category honestly matches its purpose. Read the broadcast messages guide and our opt-in guide before you do.
Frequently asked questions
What is the WhatsApp 24-hour rule?
It means you can send free-form messages to a customer only within 24 hours of their last message to you. After that, you can only send pre-approved template messages until they reply.
Does the 24-hour window reset?
Yes. Each new message from the customer restarts the 24-hour window, so an active conversation can stay open for as long as the customer keeps replying.
Can I send a normal message after 24 hours?
No. Once the window has closed you must use an approved template message. Free-form messages are not delivered outside the window.
Does the customer service window apply to the WhatsApp Business app?
The window is a WhatsApp Business API concept. If you use the standard WhatsApp Business app on a phone, this template-versus-free-form rule works differently. See our API vs app comparison.
See it working on your own conversations
Resolvenyx puts WhatsApp, email, Instagram, Facebook and web chat in one inbox, with tickets and AI agents built in. 7-day free trial, no credit card required.
Written by the Resolvenyx team
We build a WhatsApp and omnichannel customer support platform, and write these guides from what we see support teams run into. Product details are checked against the current app. About Resolvenyx