Invitation code for children's smart watches

At present, there is only one corresponding invitation code for smart watches on the market, and this request invitation code is unique, which is entered into the watch by the manufacturer when leaving the factory, and outsiders cannot know it. For example, the invitation code of Michelon smart watch can only be seen when it is turned on for the first time, or it can only be seen after the factory settings are restored, or it can be seen in the manual. If the user forgets the invitation code, he can check it by restoring the factory settings.