How to solve the problem with unsent SMS to confirm the phone?

Question

API

The task is this: to check the correctness of the phone entered by the user through the code in SMS. We send SMS via TurboSMS or Unisender (and we tried it anyway) sometimes SMS is not sent for a long time .. but after an hour or two it comes. What is the solution to this problem - because we need SMS to come within 1 minute.

Answer 1

Use google. There are a lot of services. Most provide test access.
The best solution is to conclude an agreement with the necessary operators, they will provide the opportunity to deliver SMS directly to their servers.