What are the cheap SMS confirmation services for the site?

Question

SMS

Good afternoon, the project requires SMS confirmation of user actions. The cheaper the better.
1. What are the methods of SMS delivery? (there are tariffs of 20 kopecks per SMS and there are tariffs of 1.5 rubles per SMS) what is the difference between them?
2. Which services with a high percentage of delivery are currently the cheapest?
3. Is it possible to raise your own SMS gateway, what is its cost and how does it all work?

Answer 1

1. What is the difference, most likely in the terms of the contract and the number of shipments. You need to look at specific services and their offers in order to say what are the differences
2. SMS center and SMS bliss (this one was more expensive before)
3 Perhaps, but it's not worth it