1. Create a webhook for Twilio to use in Intercom
Log into Twilio & go to the navigation menu to "All Products & Services" and "Programmable SMS" or click here.
Then click on "Create new Messaging Service" under "Messaging Services".
You can give it any name that you want.
Enter that webhook URL in both the 'Request URL' (under 'Inbound Settings') and 'Status Callback URL' under 'Outbound Settings':
Next, pick a phone number to use for the integration. This number will be the number that your users will need to text to send a message through to Intercom.
One you select a number, select "Messaging Service" in the "Configure With" dropdown menu and then the name of your webhook in the "Messaging Service" dropdown.
2. Configuring the webhook in Intercom
In Intercom, go to "App Settings" and then "Webhooks":
Click "Add Webhook", leave all the boxes unchecked except for "Reply from a Teammate", and enter this for the webhook url: