21661: 'From' number is not SMS-capable

ERROR: 21661

PROGRAMMABLE MESSAGING

ERROR

Description

Phone numbers must be SMS-capable. Visit the phone numbers page of your account portal to view a list of phone numbers that you own and to determine whether they are SMS-capable.

Possible Causes

The number you are using is not capable of sending messages.

Possible Solutions

Check that you are using a Twilio phone number with SMS capabilities. You can see your purchased phone numbers and their capabilities in the Twilio console.
Purchase an SMS capable number from the Twilio Console.