Smartphones have long "evolved" from devices designed exclusively for telephone conversation into devices (or, as they are now called – devices and gadgets), the main functionality of which is to maintain access to the Internet.
We use all available wireless access points, and when they are not nearby, we rely entirely on your mobile operator; the benefit now, each provider has a lot of package offers.
What can we say, now the mobile Internet is no longer an element of luxury, but only a technical necessity.
But what if at the right time we fail and the mobile operator, what to do if there is a message about the unavailability of the network in situations where this did not Bode well?
The answers to these burning questions will be discussed in this article.
Problems of the Issue
Unfortunately, in contrast to the" point " errors that often occur in the operation of the operating system Android or iOS, with the functional problems of the mobile network is much more complicated than similar situations with incorrectly working wireless network (Wi-Fi).
Given this, first of all, you should check a few basic points:
- There is sufficient balance on the phone balance to use the provided services, including timely paid package tariff;
- Charging the battery is sufficient to operate the device;
- Rebooting the device is not returned to the performance of the network;
- Your smartphone is disabled mode "Air";
- The correct dates and times are set;
- The subscriber is in the coverage area of the mobile network towers
Check the SIM Card Slot
The first thing to check after the above points-is to check the correctness of the slot for the SIM card. This should not be a problem in modern devices, as almost all have multiple slots.
To check enough to rearrange the SIM card in another slot, turn on the smartphone and check the quality of the network.
Special attention should be paid to the combined slots, as they are subject to the problems under consideration.
In addition, when working with two SIM cards, do not forget about the compatibility of SIM cards. Yes, it is the compatibility of SIM cards, both with the device itself, and compatibility between SIM cards.
In practice, we have repeatedly faced (on Two xiaomi smartphones) that the two sim-cards can not work with each other. That is, when they are installed in the slots on the included smartphone, one of them ceases to be displayed in the system, while the one that is inserted into the main slot. Separately and both are working properly.
What was the reason? It is not known. There is a theory that it's all about the conflicts between the tariffs of one operator.
It is possible that a visual inspection of the SIM card and the slot for it will not explain anything in this problem, they can be serviceable in appearance, but even the slightest damage (scratches, chips) can cause failures. Therefore, if none of the following in the end will not help, you should keep in mind-the need to seek qualified help in the service center.
Checking your Smartphone Settings
If your smartphone has two SIM cards, you should check the settings they use, including checking them for possible conflicts of"interests".
For example, see the following settings: (Xiaomi on Android)
- Open "Settings" and go to "Sim-cards & mobile networks";

- The first thing you should pay attention to is whether data transfer is enabled at all, the corresponding settings item must be activated;

- Next, open one of the two SIM cards (three, etc.) and select "Access Points Names";

- Click on the line with the Internet settings and check the correctness of the entered parameters, based on the data provided by the mobile operator;

If these parameters are all right, and they meet the requirements of the provider, then pay attention to the following points:
- "Set data plan" - provides a list of parameters that allow you to control the consumed mobile traffic;


- "Data roaming" - allows or prohibits the use of the mobile network as part of the roaming service.


- "Default settings" - "Internet" - sets the SIM card that is used by the smartphone in the first place when activating mobile data.

Request Settings from Operator/Provider
Perhaps the configuration of the mobile Internet at your operator has been changed, but for some reason these changes bypassed your device.
In this case, you can try to request the settings manually. How to do it depends on your operator and the contract between you.
Check for Device Updates
Also, do not forget that the mobile network works together with the operating system, and, therefore, it is also dependent on the correctness of the OS, like any other software.
Therefore, it is useful to check the availability of updates for the operating system. But here there is a difficulty, based on the specifics of the issue, because the main problem – it is the lack of Internet connection.
Unfortunately, in this version of the diagnosis without the presence of an active connection cannot do.
And to check it is enough to open "Settings" - "System apps updater" and select the desired method of obtaining update files.


Conclusion
And last, if nothing helps you can always contact your mobile operator for detailed explanations of the situation, of course, when you are in the coverage area of the network.