As soon as I passed the store, I received the advertisement information from the store. How did they know my number?

There are two ways: the first way is that when your mobile phone is using the service of the operator, the stores in North China use high-tech means to steal your location information directly from the server, and then automatically send you a text message. This is very difficult. Generally speaking, the anti-theft measures of telecommunications are not so easy to crack.

The other one is more practical. It uses its own transmission tower to receive and transmit the same frequency band as the operator. Our mobile phones are generally set to automatically access the network. When we enter this area, it is equivalent to our mobile phone automatically choosing his network as the first priority, so it takes minutes for him to send a text message to your mobile phone.