What is the reason why mobile phones often display "no service"?

If you use a vivo phone, you can handle it like this:

Impact of port number transfer: As all operators have started port number transfer, Unicom's new card has closed GSM(2G network). If the secondary card of vivo mobile phone used does not support Unicom 3G/4G, there will be no signal. It is suggested to set this card as the primary card.

5G signal is not good: Many 5G base stations will not be open all day, and operators will optimize and adjust the 5G network during the opening period. It is recommended to consult the operator's customer service to find out whether it is in the adjustment and optimization period at present or in the near future, resulting in unstable 5G signals. If not, you can use the following methods to investigate:

1. Confirm whether to use third-party magnetic attraction or metal fittings.

Check whether metal protective shell, magnetic protective shell, magnetic bracket and other accessories are used. Metal and magnetic materials can easily interfere with signal reception. It is recommended to remove the parts for inspection.

2. Confirm whether the current environment covers the carrier network.

If you are in a closed indoor environment (such as basement, elevator, etc. ), the cell phone signal may be blocked, resulting in poor signal, you can go to the outdoor environment to check. If you are in a remote area and the signal may be poor, you can use the cell phone signal of the same operator network around you to determine whether it is the cause of network coverage.

3. Check the SIM card and verify the cross card replacement.

Observe whether there is dirt or oxidation on the metal surface of SIM card, and check it after cleaning. If you use a tailored SIM card, it is recommended to replace it with a standard SIM card. Install the SIM card to other devices, or install other SIM cards to the mobile phone for comparative test to determine whether the SIM card is faulty. If it is due to the SIM card, it is recommended to reissue the card in the operator's business hall.

4. Dual telecom cards need to use VoLTE network.

If two telecom cards are used at the same time, the secondary card (non-data card) needs to open the VoLTE service and be within the coverage of the VoLTE network before registering the network.

5. Reset network settings

Resetting network settings will delete the connection records of WLAN, mobile data network, Bluetooth and other networks. You can enter Settings-System Management-Backup and Reset-Reset Network Settings-Reset Settings-Follow the prompts (you need to select the corresponding SIM card for dual cards).

Note: Enter the cloud service-data synchronization-turn on WLAN, Bluetooth, etc. Synchronize data to the cloud service. Go to Cloud Service-Device Cloud Backup-Backup Data Type-Open System Data-Return to the previous page-Back up immediately and back up some system setting data.

6, service center testing

If the above methods fail to solve the problem, please back up the data in advance, take the mobile phone and purchase voucher to the vivo customer service center for testing, enter the official website-My service outlet of vivo, select provinces and cities to inquire about the address and contact information of the local service center, or click the webpage link to search for the address of the service center.