1 The hardware problem of the mobile phone is generally common in the damage of the mobile phone card slot.
The common problem of mobile phone system is that the mobile phone has turned on the flight mode, and there is a conflict between the mobile phone system and the mobile phone card. The former can have a signal when it is turned off, and the latter needs to refresh the phone or restore the factory settings. Another common thing is that there is no network signal at present, as long as there is a cell phone signal, it can be used.
3. Mobile phone card problem: the mobile phone card is not activated, overdue, damaged, unplugged, and the SIM card is not in the same standard as the mobile phone network, so there will be no service.