The phone stopped finding the network and seeing the SIM card: the most common reasons

There are many reasons why your phone suddenly stops recognizing a SIM card. They may depend both on the mobile device and on the SIM card itself, and do not always require contacting a service center. Most often, the user can identify and fix the problem himself.

So, this guide will help solve the following problems:

1. SIM card does not work (Samsung, HTC, Pixel)
2. Why doesn't my phone see the second SIM card?
3. The phone periodically does not see the SIM card

SIM card problem

The main reasons why the phone does not see or periodically disconnects the SIM card are the following:

1. The SIM card tray of the phone itself is faulty, or the card reader contacts are dirty.
2. Mechanical damage to the contact pad of the SIM card or the formation of oxides on it.
3. Poor contact between SIM and tray contacts.
4. Software glitch.

First of all, it is recommended to put the SIM card in another, known working phone. If it is recognized and works normally there, then the problem is definitely not with it, and you should deal with the SIM holder. But modern phones do not have access to it, so the problem can only be fixed in a service center. You should not try to “clean” the contacts yourself using a needle or pin, as you can cause a short circuit (it will not be possible to disconnect the battery without disassembling it).

But you can clean the SIM contact pad yourself. But if this does not help, then the card is probably damaged. This often occurs when the user has performed an unsuccessful conversion to Micro-SIM (cutting the Mini-SIM to the required size). It can be solved by replacing the card at the office of a representative of the mobile operator (while maintaining the number).

It is possible that the card has expired. Their declared service life is 5 years, after which the manufacturer does not guarantee their proper operation. Operators even recommend changing the SIM every 2 years.

Bottom line.

I hope one of the methods definitely helped you. I am 100% sure that if the first method, which does not work on all devices, does not help you, the second method will help you. If nothing works out for you, write in the comments the model of your smartphone and what you did before the IMEI was lost and what you did to restore it. I'll try to help you.

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Dirt in the slot or on the SIM card chip

If the card is not recognized in another phone or is not recognized only periodically, then its contacts should be cleaned of dirt and oxides. This is done as follows:

1. Using an eraser. Carefully wipe the contacts. Do not wet or rub with fingers! Touch the contacts only with a rubber band. In this way, oxides are removed.
2. Using ethyl alcohol. Use exactly 96%. Pharmacies often sell a 70% solution for medical purposes, after which oxides remain. Wipe with a paper napkin. Don't use a cotton swab: it leaves lint.

And if the phone stops seeing and connecting the SIM card a couple of days after cleaning it, then this indicates wear on the contact pad. Occurs if the SIM is often removed from the tray. Only replacing the card will help.

Calls and Internet

If the smartphone supports two SIM cards, call and Internet parameters will be displayed in the gadget settings. Users can manually select the SIM card with which calls will be made and which one will be used to connect to the mobile Internet.

This way you can save money through competitive rates. For example, MTS has more profitable outgoing calls, and Tele2 has affordable tariff plans for mobile Internet.

The problem is in the phone

There may also be several reasons why a phone, including a new one, does not see a SIM card. The most likely among them:

1. The phone is locked to a specific operator and does not work with third-party SIM cards. Unbinding is only possible through the provider to which the device is locked, so you should contact him.
2. Incorrect embedded operating system settings. It occurs more often on Android, when the device is forced to switch to the CDMA band. In the Russian Federation, 2G (GSM), 3G (H, H+) and 4G (LTE) standards are used for communication. The preferred network type settings are located in the “Mobile networks” section. This is a common problem when a new phone does not recognize the SIM card.

3. The SIM card slot is damaged. Occurs if the tray is inserted incorrectly. Needs replacement. Sometimes it is enough to simply wipe the contacts of the card reader with alcohol. But this should be done only in cases where there is free access to them. If the card is inserted into a removable tray, the slot contacts can only be cleaned at a service center.
4. The SIM card holder (removable tray) is faulty. Even a small microcrack causes the SIM card chip to not fit tightly to the contacts in the phone slot. It can be fixed by replacing the tray (at a service center).

If the Android phone does not see the SIM and does not even display the icon about the absence of a card in the status bar, then it is most likely disabled. This setting is available on smartphones with Dual SIM.

What the user definitely cannot do if the phone does not see the SIM is try to place paper under the tray to increase the pressure of the card to the contacts. At best, this will end with a crack in the holder itself. At worst, the entire tray will have to be replaced.

Access Points (APN)

APN (Access Point Name) is the information that the gadget uses to connect to the mobile operator’s network: ports for processing multimedia messages (better known as MMS), data type, proxy, user name. APN technology is a gateway identifier between the Internet and a network: 2G, 3G or 4G LTE. In a smartphone, access points are used to check the IP addresses that are assigned to the gadget; to protect (encode) personal data.

By default, APN configuration is automatic. To set optimal parameters, previously users sent an SMS to the operator with a request to connect to a specific tariff plan. The response message included Internet settings that must be entered manually.

Despite this, subscribers have the opportunity to manually configure the APN, for example, if the Internet settings have gone wrong and the ability to access the Internet has disappeared. To change the APN, you need to go to your smartphone settings. Next, you need to go to the “Mobile network” section - “Access point name (APN)”.

In the upper right corner there is a menu with additional options - an icon with three dots. Here you need to select “New access point”. Now you can enter user parameters: name, APN, port, proxy, password and server. Changes can also be made to an existing access point. To do this, you need to open the desired APN and change each parameter from the list of functions.

Consequences of incorrect firmware

If the phone does not recognize the card after flashing custom Android firmware, this indicates the installation of an incompatible image for the modem. Eliminated by flashing using the original software image from the manufacturer. But if the Bootloader is locked, this can only be done at a service center (installation in EDL mode or with Fastboot pre-unlocked).

Telecom operators

This section in the SIM card settings on your smartphone allows you to select a network operator: manually or automatically. Automatic network search selects the optimal connection option. This also applies to international roaming: abroad, the gadget will choose a partner network with the most favorable rates for using the Internet, sending SMS messages and calls.

• SIM card manager, mobile networks

If you select manual mode, the gadget will begin searching for all available networks. Available options for activation will be displayed in list format - here you need to select an operator and connect to it. In this case, problems with communication and mobile data transfer speed may occur.

Removed IMEI serial number

IMEI is a unique identifier for cellular equipment and must be “sewn” into every device that supports SIM cards. If the identifier is missing, then the operator does not have the right to provide the user of such a device with access to the cellular network. The IMEI code is “integrated” into the phone itself, not into the SIM cards. You can accidentally delete it if you fail to flash your smartphone.

To check its presence, use the combination *06# (for all models). If the IMEI field contains zeros or the value “NULL”, then the identifier must be restored. This can be done if you have the original box for the smartphone (IMEI is indicated on it; for phones with Dual SIM there are two of them). It is recommended to contact an authorized service center. Falsifying an ID is a violation of the law, for which you may even be subject to criminal liability.

What could be the reasons?

The reasons for SIM errors will be identical for all mobile operators. We list all possible options:

• the SIM card connector in the phone is very clogged, the contacts have oxidized or scale has formed;
• when changing the SIM card, a mechanical failure occurred (the SIM card broke, bent, etc.);
• the subscriber did not use the card for a long time, and the mobile operator stopped servicing this network;
• incorrect settings of the mobile device.

General failure of the mobile operating system

Problems with the OS can also cause the gadget to stop recognizing the SIM. More often this occurs due to the installation of too many applications, when the RAM memory is completely filled and the system automatically unloads from it system files responsible for the normal operation of the modem. It can be resolved extremely simply: by resetting the phone to factory settings. This is done through the smartphone settings in the “System” section.

Before resetting, you should save all important data (copy it to an external drive). The procedure takes from 5 to 15 minutes. In some phones, the reset is performed through the built-in bootloader. To enter it, you need to turn off your smartphone, then hold down the power and power keys and at the same time hold down the volume up button. The reset in the system recovery menu is indicated as “Wipe Data”.

So, there are several reasons why the phone stops recognizing the SIM card. Most of them can be fixed by the user themselves. If the above recommendations do not help, then it is better to entrust the repair to an authorized service center. Their addresses can be found on the official website of the gadget manufacturer.

VoLTE

In the SIM card settings on your smartphone there is a VoLTE function - a special technology that converts voice into a data stream. With this feature, you can make and receive incoming calls over a high-speed IP link. The main advantage of VoLTE technology is the high quality of communication when communicating with another subscriber. To talk on the phone using this function, it is enough that only one gadget supports it - that of the person making the outgoing call.

Due to limited network coverage, the technology has certain limitations. In populated areas where there is no 4G, it is recommended to disable this function to increase the battery life of your mobile device.

Cellular operators do not charge additional fees for using the function - calls are paid according to the previously purchased tariff. Smartphones that were released before 2014 do not support VoLTE technology.

Eliminating poor signal levels

Users often encounter unexpected problems with Lenovo. One of them is poor Wi-Fi performance. Due to a weak connection, Lenovo Wi-Fi is poorly received. Many people think that this is due to the fault of Internet providers, but in fact this is not always the case. There are many reasons in the device itself that inhibit transmission.

Reasons affecting the slow Internet speed of the Lenovo A5000 smartphone operating according to the GSM 900/1800/1900, 3G standard:

• System failure. Reboot your phone and reconnect to the Wi-Fi network to get maximum internet speed.
• Before turning on 3G on Lenovo, update the browser and operating system of the phone to the latest versions.
• Make sure that there are no conflicts between the wireless router, as this can lead to slower internet speeds on the phone.
• Check background running applications that use the Internet connection and close unnecessary ones.
• Check if connections are being used with DNS settings. If not, you can change these settings on your device.
• Clear browsing history, cache, cookies and other unwanted browser information in a timely manner to get the required speed or switch to others.

Connect via Wi-Fi

Before setting up the Internet on Lenovo with the Android system, you need to activate Wi-Fi and connect to a specific wireless network, which is provided to users under the value 802.11 and with the letters B, N and G.

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Wi-Fi activation algorithm:

1. Before turning on the Internet on Lenovo, click the application icon on the main screen.
2. Tap the Wi-Fi text on the left side of the Settings app screen.
3. Select a wireless network from the list.
4. When prompted, enter the network password. Checking the Show Password box makes it easier to enter a long, complex network password.
5. Press the connect button, the device should be immediately connected to the network. If not, try the password again.
6. When your phone is connected, a Wi-Fi status icon appears on the touchscreen.
7. Sometimes the list of available wireless networks does not include the one you need. This is because some networks do not publicly share their names for security purposes and make them difficult to access. In these cases, the Lenovo a5000 does not connect to the Internet; you will need to additionally click the “Add” icon and enter the network name or SSID, and specify the security type. You will also need a password, which will be confirmed with the owner of the wireless network. Some public networks are open to everyone and do not require a password.

Note! There is no charge for using Wi-Fi to connect to the Internet. A wireless network puts additional strain on the phone's battery, and if it is weak, it can drain in just an hour. This must be taken into account before connecting to the Internet on your Lenovo phone. To save battery, if the user does not plan to be near a Wi-Fi access point and use the Internet, it is recommended to disable this function.

Set traffic

In the SIM card settings on your smartphone there is a separate section for managing mobile Internet. Here is the “Set traffic” function. If you use the Internet with limited traffic (for example, 5 GB per month), this feature will help you control your mobile data usage.

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High-speed broadband wireless Internet is becoming increasingly available around the world and comes with a variety of connection options. For people who use a Lenovo smartphone or tablet and are trying to choose the best connection, the availability of options can be somewhat confusing, so you need to understand this process before turning on the Internet on your Lenovo phone.