Why can't the SMS blacklist be blocked?

Unable to intercept SMS blacklist for the following reasons:

1, most of the problems are caused by the operator's server, resulting in network delay.

2, mobile phone arrears. This problem is also very common, sometimes I don't even know it myself. Just pay the phone bill at this time.

3. The storage space of mobile phone is full. When the phone's memory is full, you can't receive new messages, so you can delete some contents that occupy memory.