24-hour customer service window
Also called: service window · session window · the 24-hour rule
The 24 hours that begin each time a customer messages you. Inside it you can reply in your own words and most messages are free; outside it you can only send an approved template.
The window is the single most consequential rule in day-to-day WhatsApp operations, because it governs both what you may say and what you pay. Inside an open window, non-template messages are free and utility templates are free too — though not authentication or marketing templates, which are charged wherever they land. Outside it, a free-form reply is not possible at all — you need a template, and it is charged.
It reopens every time the customer writes, which means a conversation that stays alive stays cheap. It closes silently, which is why a reply owed at hour 23 and sent at hour 25 becomes a different, costlier, more constrained message.
A separate free entry point window runs for 72 hours instead of 24, and it opens when somebody reaches you through a click-to-WhatsApp ad or a Facebook page call-to-action. Inside that one, every message type is free.
In this product the window is shown in the composer rather than left to be remembered, and campaign audiences can be filtered on whether a contact’s window is open — which is how a send that would need paid templates gets told apart from one that would not.
What people get wrong
Assuming the window is per conversation thread or per day. It is per customer, and it restarts from their most recent inbound message — so the clock a team is racing is different for every person in the inbox.
Checked against Meta’s published documentation on 15 August 2026.
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