How to fix “Permission to send an SMS has not been enabled for the region indicated” problem on Twilio?

Enable all countries or selected countries here.

https://www.twilio.com/console/sms/settings/geo-permissions

reference:

https://stackoverflow.com/questions/47423741/twilio-permission-to-send-sms-has-not-been-enabled-for-the-region-indicated/47424927