Authy (a two-factor auth service) uses a combination of Twilio and BulkSMS (they say that BulkSMS is particularly good for Latin America). Authy explains how th

Authy (a two-factor auth service) uses a combination of Twilio and BulkSMS (they say that BulkSMS is particularly good for Latin America). Authy explains how they handle global SMS here: http://blog.leanstack.io/how-authy-built-a-fault-tolerant-two-factor-authentication-service/#bulksms http://blog.leanstack.io/how-authy-built-a-fault-tolerant-tw...