IPhone received an unknown message.

This situation is mainly caused by the contact problem of SIM card or the instability of system function. Please check and handle it in the following ways in turn: SIM card failure 1, shut down, take out the SIM card, and erase the metal problem with an eraser. 2. Replace another SIM card for testing. If it is confirmed that it is a SIM card problem, bring your personal ID card to the operator's business hall to apply for replacement. This is a free service. Mobile phone system failure After using the mobile phone for a period of time, there are a lot of software, junk files and temporary files, and the system is naturally unstable. Just restore the factory settings. This is different from reinstalling the system or restoring a backup. 1, log in to ICLOUND, back up your address book, photos and so on. If there are many files, such as big photos, it is recommended to install ITUNES on your computer and back it up. 2. Open General and select Erase All Settings. Mobile phone hardware failure If the above methods can't be solved, it is a hardware failure. Find a maintenance person to solve it. In particular, mobile phones are likely to be damaged by water and need to be replaced. However, if the cost exceeds half of the price of the machine, it is recommended to sell it and buy a new one. [Experience and Friendship Sharing] 1. Restore factory settings. There are many people who have the misconception that only by swiping a mobile phone can we solve the problems of slow mobile phone speed and stable system. In fact, it is easier and more convenient to restore the factory settings. Under normal circumstances, only when returning to the factory can not solve the problem, will the brush machine be used to solve it. Moreover, restoring factory settings is basically a one-button operation, and the operation is simple and convenient. 2. Develop the good habit of timely backup. Before restoring the factory settings, be sure to back up the data in your mobile phone, such as address book and photos. In addition, we should also develop the good habit of timely backup. It is normal that the system is unstable or the mobile phone is lost, so it is necessary to backup when using the mobile phone at ordinary times. It is recommended to use cloud disk, such as 360 cloud disk and cloud disk. They have many types of files and large spaces. The most humane thing is to back up data automatically as long as you connect to the network.