Why is there no connection service in SMS, but a mobile phone?

The reason why this happens is that after your mobile phone is turned on, it does not send a power-on signal to the switch to which you belong, so the system still thinks that you are turned off. There are two reasons for this:

1. Your local signal is not good, or the signal is good, but the error code is high (the cell phone signal is full, but the caller and the called party can't dial in and out). After booting, your boot signal disappears in the air, which makes the switch unable to receive your boot information. This kind of situation is rare, and it will recover after a period of time.

2. When you turn on your mobile phone, it only turns on the PDA mode, but does not turn on the call module, that is, it does not send a power-on signal to the switch, which is generally due to your mobile phone. It is recommended to brush defy with stable rom. Besides, I'll tell you a way. If this happens again and it doesn't work to turn on and off the phone many times, then take out your sim card and replace it with someone else's mobile phone, and it will be OK.