Until there is direct support in Promptchat for campaign sending via the Cloud Api here is a possible solution.
It´s possible to start a conversation using official WhatsApp.
By using quick replies and an api call.
This is a manual work because you need to add the message on meta business manager and set up a api call with it. but i think this is a workaround that is possible.
STEPS:
1- Create the template message on meta platform
2 - Create a quick reply with trigger for the message
3 - Create the trigger on the chatbot and connect to an api block
4- Fill the API block with the following request
curl -i -X POST https://graph.facebook.com/v18.0/{phone_code}/messages
-H 'Authorization: Bearer {token} -H 'Content-Type: application/json'
-d '{ \"messaging_product\": \"whatsapp\", \"to\": \"\", \"type\": \"template\", \"template\": { \"name\": \"hello_world\", \"language\": { \"code\": \"en_US\" } } }'
On the template name you fill with this:
So you already have the phone code, api token and message´s template name.
You just need to set up, and send the trigger for starting a conversation.
But based on this step you just need to add the message template on promptchat. and send to meta and get the message name... The hardest part was done with meta.
