Facebook Dialer Bot
A dialer bot can respond to Facebook messages instantly and schedule calls with interested prospects. Using the Graph API, your application listens for new messages and returns appointment timeslots.

Ad Space (Demo)
Here is a basic flow in Node.js using the axios
library:
const axios = require('axios');
async function reply(recipient, text) {
await axios.post(`https://graph.facebook.com/v16.0/me/messages`, {
recipient: { id: recipient },
message: { text }
}, { params: { access_token: process.env.PAGE_TOKEN } });
}

Ad Space (Demo)