SMS feature is now available to all users. To set up your SMS notifications, please click on Settings > Notifications on the dashboard.
To find out more about text / sms feature, go to Text Messaging Now Heading You Way.
Learn how to set up your SMS with tutorial guides on:
How to sign up for text / sms account with Twilio
How To Set Up Email and Text / SMS Notifications For Twilio
How To Sign Up For Text / SMS Account with Nexmo
How To Set Up Email And Text / SMS Notifications For Nexmo