There are multiple ways to prevent your network operator from blocking the SIM. When employed together, it can lengthen the time it takes for eventual SIM block or can prevent it.
1. Set some ranged delay like "15-30" between messages. You can do this from the profile page. It will select a random delay from the range for each message. The greater the difference between the minimum and maximum value, the better.
2. Use spintax feature available in v9.2 or above to randomize the message. Below is the example of spintax.
How are you?
In the above message, it will choose Hi, Hello, or Hey randomly for each message. This helps greatly to randomize the text.
3. Add random number using new feature added in v9.2 or above for more randomization. You can do this by adding "%random-10%" without quotes in your message. You can change 10 to any other value. It determines the length of the random number.