The only way to initiate a conversation with a customer on WhatsApp is to start the conversation with a pre-approved template called an HSM (Highly Structured Message).
When a customer proactively reaches out to your business, all messages during the following 24-hour window can be responded to and are at a reduced rate compared to the standard HSM pricing. This includes HSMs sent during this period. The 24-hour window is reset every time you receive an inbound message from the customer.
You can submit HSMs with your MessageBird account manager. Once submitted, WhatsApp will either approve or decline the message template. This can take up to 5 working days.
If the 24-hour window passes, the only way to restart the conversation with the customer is to send an HSM. This HSM will be charged for.
All inbound (messages sent by your customers or contacts) are free on WhatsApp.