PLEASE, CHANGE YOUR CONFIRMATION SYSTEM - IT IS NOT EVEN SUPPOSED TO WORK PROPERLY!
I really need ftp, so I asked from Twilio what is wrong. Twilio is marked as the service provider for SMS confirmation. Here is their answer:
Thank you for reaching out with this additional information. Unfortunately Twilio numbers can not be used for verification purposes as it is against our AUP so the majority of these messages will be blocked. Occasionally these messages may get through but unfortunately the platform blocks most of these messages. I sincerely apologize for any inconvenience this causes and if you have any questions in the meantime, or if I can be of assistance in any way, please do not hesitate to contact me.
Twilio Customer Support
So it is most unlikely to get a SMS confirmation. I´ve tried about 130 times, not succeeded.