Is the information center number divided into different places?

Well, different provinces/cities/regions have different information center numbers. . . At the earliest time, the information center number used to be a loophole to evade fees: the mobile phone in area A originally used the information center number in area A, but after it was manually changed to the information center number in area B, there would be a bug in sending text messages. The mobile phone is in area A, but it uses the information center number in area B to send and receive short messages (the system will judge that it is roaming). The billing system in Area A will find that the mobile phone information roams to Area B, and the charge should be charged in Area B, so there is no right to charge in Area A where the mobile phone is located at present, and the mobile phone using the information center number in Area A becomes a free SMS. Later, this loophole was plugged, but it showed that the information center number of different provinces/cities/regions would be different, and the sim card would be automatically modified to the local information center number every time it roamed to a place.