TL;DR
The conversation window is a 24-hour window that opens every time a customer sends a message to a business. Inside the window, you can send any type of message. Outside the window, you can send only message templates that Meta has approved. This is the foundational rule of the WhatsApp Business API, and it’s the very reason message templates exist.
How the conversation window works
Meta built the WhatsApp Business API so that businesses can’t send customers free-form messages whenever they like. The rule is simple:
- A customer sends a message to the business – a 24-hour window opens.
- Within those 24 hours – the business can send the customer any message: free-form text, an image, a video, a document, buttons, lists.
- After 24 hours from the customer’s last message – the window closes. The business can send only message templates that were pre-approved by Meta.
Every new message from the customer resets the count to a fresh 24 hours. If the customer replies every few hours, the window stays continuously open. If they stop replying, the window closes after 24 hours.
The reason for the rule is protection against spam. If any business could message any customer whenever it wanted, WhatsApp would turn into a noisy marketing channel and users would leave the platform. The rule ensures that a business can reach out to a customer on its own initiative only with pre-approved content, and with the customer’s consent (an opt-in).
What you can send in each situation
| Customer’s status | What the business can send |
|---|---|
| Sent a message in the last 24 hours | Any type of message: text, media, buttons, interactive elements. Message templates too, if you want. |
| Sent their last message more than 24 hours ago | Approved message templates only. |
| Never sent a message to the business | Approved message templates only, and only with a valid opt-in from the customer. |
One line to remember: if the customer hasn’t written to you in the last 24 hours, you’re in a message-templates-only world.
How this affects day-to-day use in Mumble
Every sending feature in Mumble follows this rule. In practice:
- Campaigns and broadcasts – always based on message templates. They’re sent to an audience that’s mostly outside the window, so there’s no other way.
- The chatbot and Dolores AI – reply to a customer who is writing right now, which means always within the window. They can send free-form text, buttons, menus, and anything else needed.
- Chatting with an agent – same rule. As long as the customer wrote in the last 24 hours, the agent types freely. If 24 hours have passed, Mumble won’t allow sending free-form text – you’ll have to choose a message template.
- Sending a follow-up after a few days – always requires a message template. Even if the conversation ended on a good note a week ago.
- The first message to a new customer – always a message template, always with an opt-in.
Cost: how the conversation window affects Meta billing
Meta charges per conversation, not per message. A conversation is a 24-hour window with one customer. All the messages within that window count as a single conversation for billing.
The conversation type affects the price:
- Service – a conversation the customer opened. In Israel and many other countries, Service conversations are free or very low cost under Meta’s 2024-2026 pricing.
- Utility – operational updates such as order confirmations. Mid-range pricing.
- Marketing – promotional content. The highest pricing.
- Authentication – verification codes. The lowest pricing.
Meta’s pricing changes periodically and varies by destination country. Before launching a large campaign, it’s worth checking the current pricing on Meta’s website.
Common issues and troubleshooting
I tried to message a customer and Mumble won’t let me
Reason: more than 24 hours have passed since the customer’s last message, the window has closed, and you can’t send free-form text.
Fix: send an approved message template. When the customer replies, the window reopens and you can go back to free-form writing.
The chatbot stopped working mid-flow
Reason: the customer stopped replying, 24 hours passed, and the bot can’t send the next message because the window has closed.
Fix: design the flow so that steps requiring a customer reply don’t wait for days. If you need to follow up with the customer after the window, use a message template via an automation or a re-engagement campaign.
I sent a campaign to customers I spoke with yesterday and didn’t understand why it cost money
Reason: campaigns are always sent as message templates, and every message template opens a new conversation in the template’s category (Marketing / Utility / Authentication) – even if the customer is inside an open conversation window. Billing follows the message template’s category.
Fix: if the customer is still inside the window, the conversation is free anyway and there’s no need for a campaign. Message them directly from the chat. A campaign is the right tool for customers who are outside the window.
I want to send a follow-up a week after a conversation
Reason: after a week the window has long since closed, and you can’t send free-form text.
Fix: build a dedicated message template for the follow-up (usually in the Utility category if it’s an operational update, or Marketing if it’s a promotional attempt), get it approved by Meta, and send it via a campaign or through the chat once it’s approved.
Related articles
- The WhatsApp Message Templates Guide
- Creating a Message Template
- The Complete WhatsApp Campaign Guide
The bottom line
The 24-hour conversation window is the boundary between “free replies in any format” and “approved message templates only.” Every sending action in Mumble – from regular chat to campaigns, chatbots, and automations – operates within this boundary.