Key takeaways
- When a customer messages your business on WhatsApp, a 24-hour customer service window opens. Each new message from them starts it again.
- Inside the window you can reply however you like. Outside it, you can only send a message template that Meta has approved.
- Templates come in three categories, marketing, utility and authentication, and Meta reviews each one before you can send it.
- Message only people who opted in, and stop when they ask. Meta bills each delivered message to your WhatsApp Business account.
What the window is
WhatsApp calls it the customer service window. It opens when a customer messages or calls your business, and it lasts 24 hours. If they write or call again before it runs out, the clock resets to a full 24 hours.
The window is really about who started the conversation. While a customer is talking to you, you can answer freely. Once they have gone quiet for a day, any new message from you counts as you starting a conversation, and that takes a template.
| Situation | The window | What you can send |
|---|---|---|
| A customer asked about delivery an hour ago | Open | Any reply: text, images, files, buttons or lists |
| They wrote again this morning | Open, and reset to 24 hours | Any reply |
| Their last message was two days ago | Closed | An approved template only |
| They never messaged you, but opted in on your website | Closed | An approved template only |
Inside the window and outside it
Inside the window, a conversation works like any chat: answer questions, send a photo of the product, share a document or offer quick-reply buttons. Automations can answer too, as long as people can reach a person. The WhatsApp Business Messaging Policy asks automated chats to offer a clear way to a human, such as a hand-over to your team.
Outside the window, the only option is a message template: a message you write in advance and submit to Meta, with placeholders for details such as the customer's name or an order number. Templates are how you send a delivery update the next day, remind someone of an appointment or announce a sale to people who signed up for offers.
The three template categories
| Category | Use it for | Examples |
|---|---|---|
| Marketing | Promotions, offers, news and invitations | A weekend sale, a new menu, an invitation to come back |
| Utility | Updates about something the customer already did or asked for | Order confirmed, appointment moved, payment received |
| Authentication | One-time codes that confirm someone's identity | A sign-in or verification code |
Pick the category honestly. A discount squeezed into an order update is marketing, not utility. The category also affects what Meta charges for each message.
How template review works
Meta reviews every template when you create or edit it, and you can send it only once its status is approved. A template has up to four parts:
- Header (optional): a short line of text, or an image, video or document.
- Body: the message itself, with placeholders. Meta asks for a sample value for each one, so it can see how the message reads.
- Footer (optional): a short closing line, often how to opt out.
- Buttons (optional): quick replies, website links, a call button or a copy-code button.
Write templates the way you would want to receive them: name your business, say why the person is getting the message, use placeholders only for details that really change, and skip vague teasers.
Opt-in and opt-out
Before you start a conversation with someone on WhatsApp, you need their permission. Meta's opt-in rules come down to three things: the person gave you their number, they agreed to hear from your business, and the opt-in named your business clearly. How you collect it is up to you, for example with a form on your website, a text message, a phone call or a paper form at the counter.
- Say what people will get, such as order updates or offers, and ideally let them choose.
- Keep a record of who opted in, when and how.
- Honor every request to stop, and make stopping easy, for example by telling people they can reply STOP.
People can also block or report your business, and WhatsApp may limit how many messages you can send based on that feedback. A new business starts with a low messaging limit, the number of people it can start conversations with in a rolling day, and Meta raises it for businesses that verify and keep their message quality high.
What WhatsApp messages cost
Meta charges for WhatsApp Business messages, and the bill goes to the payment method on your WhatsApp Business account. Prices are per delivered message and depend on the message category and the recipient's country, while messages customers send you are free. Meta updates its prices and free allowances from time to time, so check Meta's WhatsApp pricing before you plan a large send, rather than relying on a figure you saw elsewhere.
Postocial doesn't add a fee per message: WhatsApp is included in Premium and higher plans.
How Postocial helps you work within the window
- A countdown on every chat. The unified inbox shows how much of the 24 hours is left on each WhatsApp conversation, so you can answer the ones about to close first.
- Templates when the window is closed. Once a window closes, the inbox offers to send an approved template instead of a regular reply.
- Automations that check the window. A flow can test whether the window is open, and WhatsApp steps that need an open window can fall back to an approved template.
- Template-only broadcasts. WhatsApp broadcasts always use approved templates, and contacts without a recorded WhatsApp opt-in are left out of marketing templates. Opted-out contacts are skipped.
- Local-time sending. Schedule a broadcast for each contact's own time zone, so nobody gets your offer at 3 a.m.
- A template copy library. 64 ready-made marketing templates across 8 industries, written with Meta's review rules in mind, to customize or submit as they are.
None of this changes Meta's rules: Meta still reviews every template and decides what it approves. The WhatsApp set-up guide walks through connecting your number and sending a first template.
A checklist before you send
- Every recipient opted in, and you know when and how.
- The message is a reply inside an open window, or an approved template.
- The template's category matches its content, with no promotion hidden in a utility update.
- Placeholders hold real values, and the preview reads well on a phone.
- The message says who you are and how to stop getting messages.
- It goes out at a sensible local time for each recipient.
- You've checked Meta's current prices for the countries you're sending to.
- Someone on your team is ready to answer the replies.
Sources
Network rules, limits and specs in this article come from these pages, checked on November 1, 2026. Networks change them from time to time.
Meta for Developers
- developers.facebook.com/
docs/ whatsapp/ cloud-api/ guides/ send-messages - developers.facebook.com/
docs/ whatsapp/ business-management-api/ message-templates - developers.facebook.com/
docs/ whatsapp/ business-management-api/ message-templates/ components - developers.facebook.com/
docs/ whatsapp/ messaging-limits - developers.facebook.com/
docs/ whatsapp/ pricing - developers.facebook.com/
docs/ whatsapp/ overview/ getting-opt-in