The WhatsApp 24-hour customer service window, explained

The WhatsApp 24-hour customer service window is the period after a customer messages you during which you can reply with free-form messages. Once 24 hours pass without a new customer message, you must use an approved template to re-open the conversation.

Why does the window exist?

It keeps WhatsApp conversational and consent-based: businesses respond to customers in real time, but cannot send unlimited unsolicited messages. Each new inbound message from the customer resets the 24-hour clock.

Inside vs outside the window

• Inside the window: send any message type — text, media, voice notes — freely.
• Outside the window: you must start with an approved template (e.g. an order update or reminder); once the customer replies, the window re-opens.

How does it affect WhatsApp Business Calling?

VoiceStream respects the window automatically: in-window calls dial straight through, while out-of-window calls follow the required permission flow. Your agents don’t have to track the clock — the platform handles it.