A conversation is the messages sent within a window which last for 24 hours starting from the first message that was sent by business.
Who initiated a conversation?
A conversation can be initiated by either a customer (user-initiated) or business (business-initiated), but the 24 hour window will only begin with the first message sent by business.
Can you initiate a WhatsApp conversation without a template message?
If the business initiates the conversation without an open customer service conversation, then it must be initiated with a template message. This will begin the business-initiated conversation based on the category on the message template sent to initiate the conversation (Utility, Authentication or Marketing).
If there is no active conversation but there is an open customer service conversation, the business is able to send a non template/free form message. This will begin a user-initiated conversation (Service).
During the service conversation only non template/free form messages can be sent. If a template message is sent, it will initiate a new conversation based on the message template sent (Utility, Authentication or Marketing).