Text message notifications are provided by Twilio. Twilio is a paid service but cheap to use. Please go to the Twilio website and start your Free Trial.
Complete The form as shown below -
Click on Get a Twilio Number
Copy the Account SID, AuthToken, Phone Number and go to Settings>Notification and paste it under Text Message Notifications
With this trial number you can only send notification to Verified Phone Numbers.
In your Twilio Dashboard click on Phone Numbers>Manage>Verified Caller IDs and add your own phone number
Then in your Rovbots Chat Dashboard go to settings>notificatiosn and under Text notification click on configure URL and copy the URL
Then in your Twilio Dashboard go to Phone number>Manage>Active Phone number and click on the phone number
Paste the URL copied in previous step as shown below after clicking on your Twilio Phone Number -