Why can I receive local information when I turn on my mobile phone?

Because the mobile phone is connected to the local base station, you can send this short message directly. This regional short message is controlled by telecom operators, who can intervene in sending short messages. This truth belongs to a physical structure with the positioning function of the base station of this station, which is conveyed by the nearby base stations. The difference is the direction is different. One is that the mobile phone actively inquires the ID of the base station, and the other is that the base station actively sends information to the mobile phone in the coverage area.