...
The providers we support are:
Twilio
MessageBird
WhatsApp 24-hour customer service
...
window
Service window
When a customer contacts you on your WhatsApp Business API account, you are given 24 hours to respond. This is known as the Customer Service Window, and was put in place by WhatsApp to combat spam. During this period, you can communicate freely with your customer, with no limitations on the content or type of your messages.
...