Is it free to send short messages on the SMS platform in OA system?

Here's the thing. Generally, OA provided by OA suppliers has the number of short messages. For example, if the supplier provides you with 1000 short messages, you don't have to spend money within 1000. This is paid by the supplier. Generally speaking, suppliers cooperate with several major communication operators. When the number of your text messages exceeds the number provided by the supplier, you may have to pay for it yourself.