Which SMS verification code API is better?

If your company is very big, you can directly seek cooperation from China Mobile (the requirements are very high, and it is estimated that it will take half a year to complete the formalities). Usually looking for an agent. Which is better for domestic SMS? The question is actually which agent is better. In the end, the three operators of China Mobile Telecom Unicom will definitely be able to send short messages. This market is so chaotic that the top few are not necessarily the best, you know. It's hard to tell this from that. We used the Ding Dong cloud short message platform, which was ok. Mainly good service attitude. Interface documentation is available. In fact, reading the document shows that texting is very simple. However, the supervision is very strict now, and it is ok to issue verification codes. Sending spam messages is almost impossible.