Like you currently use the Facebook API for direct integration with Facebook Messenger, it would be great if you could integrate with the proper Whatsapp API: https://developers.facebook.com/docs/whatsapp/cloud-api/get-started
This would be beneficial for two reasons.
> Saves any costs associated for Twillio
> Means that we can use official landline numbers registered with Whatsapp Business instead of having a random twillio number which is inconsistent.
> We have the ability to still use the Whatsapp for Business App to initiate and reply to conversations in addition to Missive. Just like with Messenger.