How does Unicom block the letter business by sending short messages?

Due to the different policies of different cities, there are different ways to block, cancel or inquire about Unicom's telephone charges. For example, Guangdong Unicom provides the function of shielding information services. Guangdong Unicom users can send "PBYW" to 10655 133 and "GBYW" to 106559342 to apply for blocking Unicom's convincing function, and send short messages to 10655 1438,/for free. In other provinces, you can contact local customer service for details.