I reviewed another post on the problem of not receiving the OTP Code from Vivaticket and not being able to purchase tickets. The other person who posted the question finally seemed to receive their code via email after multiple emails were sent to Vivaticket. I'm having the same problem and was wondering if there is another solution. I did enter +1 for the country code, have contacted Verizon (who assures me the problem is not on their end), have checked my cell phone settings and also my blocked number/spam folder. I have sent a few requests to Vivaticket but no response yet.
We're having the exact same issue (and we're with T-Mobile). I'm pretty sure the issue is on Viva Ticket's end. We've tried all permutations of how to enter the cell phone number. I've seen many posts from people saying they ultimately had to enlist the help of someone with an Italian cell phone to get the OTP. Please keep us posted if you find an alternate resolution.
I had the same experience. I emailed the VivaTicket help desk, describing the problem, and they emailed me the OTP digit code the following day to complete the purchase. On another forum, this link has been provided to access the help desk. https://shop.vivaticket.com/en/assistenza Good luck!