Is the short message given by monthly traffic free?

If you understand that there is no such thing as a free lunch, then you can be sure that SMS is not free. It is because you don't know what traffic is, what is the traffic of 1M (megabytes), whether it is a quantitative or variable algorithm, and so on. For a simple example, a short message is only a few k on average, and 1M is 1000K. So taking 1M is enough for you to send dozens or even hundreds of short messages. The rules of the game of monthly subscription are usually several hundred meters, and zero in the current month is called monthly subscription. And sending you text messages, that is, hundreds, takes less than a few meters. Then, the zeroed megabytes are enough for you to send tens of thousands of text messages. This is a way of charging, also known as "fishing fee"