The 24-hour customer service window is the period after a customer sends a message to a business on the WhatsApp Business API during which the business can reply with any free-form message, with no approved template needed and no Meta charge. Every new message from the customer restarts the 24 hours. Once the window closes, the business can only reach that customer with an approved template message, which Meta bills per message. The rule exists so that businesses can only start conversations in controlled, pre-approved ways, while customers can always get a quick, free reply.
Why it matters
For a food business taking orders on WhatsApp, almost everything useful happens inside the window. The customer messages to order, so the menu, cart, payment link, confirmation, preparing and out-for-delivery updates all fall within 24 hours of that first message and cost nothing. The window matters most for what happens later: a review request the next evening, a "we miss you" nudge after three weeks, or a festival menu. Those are outside the window and need templates. Understanding this boundary is the key to reading WhatsApp API pricing without surprises.
Example
A customer orders at 1:00 pm on Monday. The window is open until 1:00 pm Tuesday. The restaurant sends the confirmation at 1:02 pm, "out for delivery" at 1:40 pm and "delivered, how was it?" at 2:10 pm, all free. At 7 pm the customer replies "great, thanks", which restarts the window to 7 pm Tuesday. On Wednesday evening the restaurant wants to send a weekend offer; the window has closed, so it must use an approved marketing template, which in India costs well under a rupee. For 1,000 customers that is under ₹1,000 for the send, and every reply those customers send reopens a free window. Template wording and approval are covered in template message approval.
On Tezzu, the ordering bot and order confirmations run inside the customer's window, and campaigns to customers outside it go out as templates paid from a prepaid wallet.