The WhatsApp 24-hour customer service window, explained

The customer service window is the most important rule on the WhatsApp Business API. Understanding it saves you money and failed messages.

The rule

When a customer messages you, a 24-hour window opens. Inside it, you can send anything: text, images, documents, buttons, lists, forms, products. When it closes, you can only send an approved template. Each new message from the customer restarts the 24 hours; your own messages don’t.

What it means for charges (from 1 October 2026)

• Free-form replies inside the window are service messages. Each business number gets 1,000 free a month; after that Meta charges them.
• Utility templates sent inside the window are now charged too.
• Marketing and authentication templates are always charged.

See WhatsApp API pricing in India for rates.

Keeping the conversation going

• Reply quickly. An agent replying in minutes keeps the customer inside the window. A Separate Inbox for Each Number with round-robin assignment helps.
• Ask a question. A reply with buttons (“Yes, book it” / “Not now”) invites the customer to answer, which reopens the window.
• Use the right template after 24 hours. A utility template for a follow-up on their order, a marketing template for a new offer.
• Automate follow-ups. A no-reply trigger in a flow can send a template if the customer goes quiet.

How MeAPI helps

The inbox shows a live countdown on every chat. When the window has closed, the composer switches to Send template, and the API refuses free-form messages with a clear WINDOW_CLOSED error instead of failing at Meta. More in the 24-hour window guide.