Comment by tripue

We faced the same problem at Zenly and had to build our own anti-spam strategies to prevent it since Twilio was not taking care of the problem for us. We used multiple providers to improve our conversion rate and reduce cost. We are now building this as a service https://www.ding.live/ and are seeing huge improvements for our first customers in term of cost savings and conversion rate. Feel free to reach out if it could be any interest to you [email protected].