There is new api now.
How does the Messenger Platform work?
When a person sends a message to a business on Messenger and as long as this Page uses an app to partially or fully automate conversations, the following will happen. The Facebook server sends webhooks to the URL of the business server, where the messaging app is hosted. Using the Send API, the app can respond to the person on Messenger. In this way, developers can build guided conversations to lead people through an automated flow or build an app to serve as a bridge between your agents and your business presence on Messenger.
The Messenger Platform does not require any payment to use. It is meant for businesses to handle inquiries from their customers. Once you build your experience for your customers to interact with, you can then leverage Ads to bring people to your experience, like for example Click-to-Messenger Ads or Inbox Ads.
What does a Messenger for Business experience look like?
We have a sample eCommerce business that you can chat with on Messenger called Original Coast Clothing.
Chat with Sample Business Here
How do I get started?
You can get started by creating a test page and test app that allows you to try your experience within Messenger. We have some examples that can get you started. Once your app is ready to deploy, you can submit it for review. When your app passes our review process, it will be ready to interact with the public.
In order to get started, you will need Messenger, a Facebook Page, and a url where the webhooks to be sent to.
Here is a step-by-step guide to deploy the above experience into your test page to get you started.
Ready to Build?
Get Started
https://developers.facebook.com/products/messenger/
https://developers.facebook.com/docs/messenger-platform/reference/send-api/