send_message with type: template is how an assistant starts a WhatsApp conversation, or messages someone after the 24-hour window has closed. The template must already be APPROVED. A template that is still pending or rejected returns TEMPLATE_NOT_APPROVED, and the assistant does not describe that call as delivered.
Ask this
What the assistant calls
1
Read approved templates
list_templates defaults to status APPROVED. The name and language on the send must match one of those rows.2
Send
send_message uses type: template and named variables such as customer_name. Pass phoneNumberRef when the account has more than one number.send_message only after you ask it to send. A failed send was not delivered.
If you want it later, use Schedule a template. Field rules are on Messages.