Why can't I send a Twilio Verify SMS to caller in Mexico?

Question

Setup

I have been testing my Twilio app successfully for a while now using two USA-based numbers (+1 country code). The Verify tokens have been delivered successfully via SMS and the verification check statuses come back 'approved'. Life is good! 😎

Problem

This morning I tried to testing my app with a caller from Mexico (+52 country code), and it totally failed. The caller did not receive the Verify SMS. 😩

Twilio::REST::RestError ([HTTP 403] 60605 : Unable to create record
The destination phone number has been blocked by Twilio. MX is blocked for sms channel in all services
https://www.twilio.com/docs/errors/60605

Aside from the "Unable to create record" message (I don't know what kind of record it is referring to), the message:

The destination phone number has been blocked by Twilio

makes me think my caller's number specifically has been blocked (is he on some dark web Internet's Most Wanted list!?). 🚔 The latter message:

MX is blocked for sms channel in all services

made my heart sink like all of Mexico was barred from receiving any kind of sms whatsoever. 🙅

Possible Cause

Visiting the URL from the error message led me to believe that perhaps somehow my Twilio account had been flagged (maybe I was manually testing too much in the preceding days):

The destination has been disabled due to suspected fraudulent activity or for possible security reasons.

Question

Why wasn't Twilio able to deliver the Verify SMS to the caller from Mexico? 🤔

Answer 1

I contacted Twilio Support and they promptly pointed me in the right direction. Apparently, only a handful of countries are enabled to receive Verify SMS by default. There are some bad dudes out there who abuse the communications network/system, so this is why we can't have nice things. Twilio Support to the rescue! 🦸

In order to send Verification SMS to phone numbers in a specific country, please ensure the destination country's Verify geo-permissions are enabled. You can enable them here: https://console.twilio.com/us1/develop/verify/geopermissions

For more information, please see https://www.twilio.com/docs/verify/preventing-toll-fraud/verify-geo-permissions

Screenshot of what to expect (search for country and check the box)