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The WhatsApp 24-hour window: what you can send, and what it now costs

Last updated 23 October 2026

By Mu'men Tayyem, founder, M4B1 (Jabee)

Short version. A customer messages you. That opens a 24-hour window in which you can reply with anything you like, in your own words. Each new message from the customer resets the window to 24 hours; your own replies do not. When it closes, the only way to reach them is an approved template, until they write again. Since 1 October 2026 the replies you send inside that window are billed, after 1,000 free per number per month.

Almost every confusing thing about WhatsApp for business is downstream of this one rule.

What opens the 24-hour window?

A message from the customer. Nothing else. Meta calls it the customer service window, and the name is the explanation: it exists so businesses can answer people who asked something, and not so businesses can start conversations with people who did not.

While it is open you can send free-form messages — text, images, documents, buttons — with no template and no approval. These are service messages.

What resets it, and what does not

This is the part people get wrong, and it is worth being precise.

Every message the customer sends resets the window to a fresh 24 hours from that moment. A conversation that goes back and forth over three days never closes, because the customer keeps reopening it.

Your own messages reset nothing. Replying at hour 23 does not buy you another day. The clock is tied to the customer's last message and only to that.

So a thread where you answered and they went quiet is on a countdown you cannot extend. At hour 25, a free-form send to that number is rejected by the API rather than delivered — which, if your code does not check, reads as a customer who never replied rather than a message that never arrived.

What can you send while it is open?

Anything. That is the whole value of the window. Free-form text in your own words, an image of the item they asked about, a PDF quote, a voice note, a list of buttons.

You can also send templates inside the window, and businesses often do without noticing — an order-shipped notification that happens to land during an open conversation is still a utility template, and since 1 October 2026 it is billed as one.

What happens when it closes?

You lose the ability to write freely to that customer. The only way back in is a template you wrote in advance and Meta approved. If the customer replies to it, a new 24-hour window opens and you are back to normal conversation.

This is why "just follow up tomorrow" is not a thing you can casually do on WhatsApp. Following up after a day requires an approved template, in a category Meta will charge you for, and a marketing template to somebody who did not opt in is how businesses collect quality-rating damage.

Is the 24-hour window free?

It was. It is not any more, and this is the change most worth knowing.

Until 1 October 2026, replies inside an open window cost nothing — the window was, in effect, the free part of WhatsApp. From that date Meta charges per delivered service message, with 1,000 free per business phone number per month, resetting monthly and not rolling over. After the allowance, the rate is your customer's market utility rate: $0.0157 in the UAE.

Utility templates sent inside an open window also became billable on the same date. Those had been free since 1 July 2025, so a notification flow that cost nothing a year ago has a line on the bill now.

The worked arithmetic for a Gulf business is in what you actually pay after 1 October.

What is the free entry point window?

One genuine exception, and it is underused.

When a customer reaches you by tapping a Click-to-WhatsApp ad, and you respond within the customer service window, that conversation runs in what Meta calls a free entry point window — and marketing, utility, authentication and service messages inside it are not charged.

If you are already paying Meta for the ad, the conversation it produces is not billed on top. For a business running paid acquisition into WhatsApp, that changes the cost comparison between a CTWA campaign and an organic enquiry, in favour of the ad.

How this shapes a support workflow

Three practical consequences we build around.

Answer fast, because the window is a deadline, not a courtesy. A customer who messages at midnight and gets an answer at nine the next morning is still inside the window. One who messages on Friday and gets an answer on Sunday is not, and reaching them now costs a template send and their patience. This is the entire argument for an assistant answering out of hours: not that replies at 2am are impressive, but that a reply at 2am is free and a reply on Monday is not.

Check the window before you let a human reply. When an owner answers a customer from their phone hours later, the send can fail for a reason that has nothing to do with what they typed. Jabee checks the window first and says plainly that the customer last wrote more than 24 hours ago and will have to message again — rather than accepting the reply and silently dropping it.

Do not send holding messages. "Thanks, someone will get back to you shortly" is now a billed message that answered nothing, and it does not extend the window either, because your messages never do. Either answer the question or fetch a person; a message that does neither costs the same as one that does.

Frequently asked questions

How long is the WhatsApp customer service window? 24 hours from the customer's most recent message. Each new message from them resets it to a fresh 24 hours.

Do my replies reset the 24-hour window? No. Only messages from the customer reset it. Replying at hour 23 does not extend the window by a minute.

What can I send after the window closes? Only a message template you wrote in advance and Meta approved. If the customer replies to it, a new 24-hour window opens and you can write freely again.

Are messages inside the 24-hour window free? Not since 1 October 2026. Each business phone number gets 1,000 free service messages a month, after which each delivered reply is charged at the customer's market utility rate. Utility templates sent inside an open window also became billable on that date, having been free since 1 July 2025.

What happens if I send a free-form message after 24 hours? The API rejects it rather than delivering it. If your code does not check the response, that looks like a customer who never replied rather than a message that never arrived.

Is there any way to message inside the window for free? Yes, through a free entry point window. When a customer reaches you from a Click-to-WhatsApp ad and you respond within the customer service window, messages in that conversation are not charged.

Sources

Written by Mu'men Tayyem, founder of M4B1 in Dubai. These are notes from building Jabee, a WhatsApp AI assistant that answers customers from a business's own website and calls the business's own APIs as agent tools.