How to judge that the Apple baseband is broken?

The symptoms of Apple's mobile phone baseband are as follows:

1, the most obvious thing is that there will be no signal in the cell phone signal bar. Or the baseband of Apple's mobile phone is broken, there is a search or no signal in the signal display area, it is impossible to make and receive calls, and the cellular mobile data is displayed incorrectly.

2. In addition, click Settings-Modem item in the "About this machine" option is blank.

Mobile phones usually consist of two circuits, one is the advanced processing part, which is equivalent to the computer used; The other part is baseband, which is equivalent to the modem used. What network standard does the mobile phone support (GSM, CDMA, WCDMA, TD-SCDMA, etc.)? ) is determined by it, just like the difference between ADSL modem and ordinary narrowband modem.

Make phone calls, surf the Internet, send text messages, etc. With a mobile phone, all instructions (usually standard AT instructions) are sent to the baseband part through the upper processing system, and are processed and executed by the baseband part. After the baseband part is processed, a logical channel will be established between the mobile phone and the wireless network, and voice, SMS or Internet data packets will be sent through this logical channel.

Extended data

The solution to the baseband fault of mobile phone is as follows:

1, download the latest version of itunes on the computer side, otherwise unknown errors may occur during reinstallation.

2. Turn off the iphone when it is connected to itunes. Press and hold the Home button and the Shutdown button at the same time 10 second, release the Shutdown button, and then continue to press and hold the Home button until you see that the devices on the computer are recognized as DFU. When prompted by the computer, release the home button, select the restore option button on itunes, and click OK to restore in the pop-up selection box.

3. Next, itunes will pop up a page, prompting that all contents will be erased and will be verified and restored with the Apple server. When the verification and file extraction are completed, iTunes will automatically reinstall the downloaded firmware version for the iphone, and then reactivate the iphone after the installation is successful.