21608: The 'to' phone number provided is not yet verified for this account.

You have attempted to send a message to an unverified phone number while using a trial account.

To prevent spam, trial accounts can only send messages to phone numbers you've verified with Twilio. You must upgrade your account to remove this restriction.

• Verify the phone number you wish to reach via the Twilio console. See step-by-step instructions in our guide to working with your trial account. Note that you will need access to this device to receive the call or text with your verification code.
• Upgrade your Twilio trial account to a full paid account to remove this restriction by providing your payment information via credit card or Paypal on the console billing page.