Why does 2 SIM cards work? What are the advantages and disadvantages of dual SIM phones?

A SIM card is a necessary part of any cell phone. Without a SIM card, as we call it in modern times, it is impossible to send and receive messages and calls. Unfortunately, no one is immune from a situation where a SIM card suddenly stops working. Or, for some reason the new SIM card refuses to be friends with the phone. The phone immediately reports this problem, asking you to insert a SIM card, although it is already inside.

Action plan:

What to do in such a situation? How to find out, why is the sim card not working?? Below is a detailed action plan.

1. Open the phone, inspect the SIM card, evaluate its location in the slot. Perhaps the SIM card has moved slightly, so its contact with the phone is lost. If in your phone the SIM card needs to be inserted under the battery, and not into the card reader next to it, then there is a high probability that the contacts of the SIM receiver and the SIM card simply do not touch. Try pressing the SIM card to the slot using a small sheet of paper folded several times. Place the folded sheet between the SIM card and the battery and reassemble the phone. Perhaps contact between the parts will be restored and the SIM card will start working again.
2. Carefully inspect the contacts of the SIM receiver and SIM card. Are they dirty? They may be the reason why SIM card stopped working. Wipe the visible contacts with a regular eraser, return the SIM card to its place and reassemble the phone. Works?
3. Bend the SIM card slightly so that the side with the contacts is convex. With prolonged use, the SIM card heats up and becomes deformed, and then the SIM card contacts do not reach the slot.
4. Insert another SIM card into your phone. The best option would be a SIM card from another operator. If it works, then the problem is with your SIM card: it is faulty. If the phone does not see the new SIM card, it means that the problem lies with it.

Why did it happen so?

In a conflict between the SIM card and the phone, as a rule, one of them is to blame.

If the phone is to blame

• Some phone models are “locked” for a specific operator, so such a phone simply will not see a “non-native” SIM card.

• With cell phones with two SIM cards, it often happens that SIM card slot does not work when the second one is working. Therefore, when inspecting the phone, you should insert the “doubtful” SIM card into both the first and second slots.

• Some physical damage can have a detrimental effect on the phone's performance. For example, if water gets on the device (it fell into a puddle, or it rained on it), over time the contact between the slot and the SIM card will be broken due to oxidation. You can try to solve this problem yourself: disassemble the phone and wipe with a napkin the joints of the cables responsible for the communication module. If even after cleaning the SIM card does not work, then you will have to take the phone to the service center and repent there that you didn’t look after your little friend.

Please note that the phone does not immediately respond to physical damage such as being dropped or exposed to water. It works as usual for a while, but later breaks down. Therefore, if you have a phone in your hands that does not see a SIM card, try to remember if your friend had to endure any troubles. Even a sudden change in temperature is detrimental to the operation of a SIM card. You bring your phone from a cold winter into a warm house, and moisture condenses inside the device. The solution here is simple: disassemble the phone, remove the SIM card and wipe it with a soft cloth.

If it's Sim's fault

• Some SIM cards have an expiration date. If a SIM card is not used for a long time, it becomes blocked and turns into a useless plate. Also, the SIM card may be blocked due to a negative balance. Each operator has its own rules, and you need to know them.

• Some mobile operators allow SIM card activation only after the first paid action. As a rule, when purchasing a SIM card, you are informed about its correct activation.
• Many modern touchscreen phones use a cropped SIM card rather than a full-size one. Sometimes owners of iPhones and other mobile devices cut the SIM card on their own, and then discover that cut SIM card does not work. Perhaps the reason lies in improper pruning, so it is better to entrust this process to specialists in service centers. But first, if you mini sim card not working, inspect it for contamination, restart the phone. The same inspection should be carried out if micro sim card not working. After all, there remains hope that you can solve the problem yourself.

We contact operators

Each mobile operator is interested in the loyalty of its customers, so in almost all cities there are service centers where you can contact with your problem.

Phones with two SIM cards will be relevant as long as there is at least some competition in the mobile communications market. Today, operators attract customers with a wide variety of tariff plans, offering favorable rates for calls under various conditions.
And man, as you know, is always looking for where it is better. And we often carry with us several mobile phones equipped with packages from different operators. And therefore, the decision in favor of a “dual-SIM” device is often quite justified.

What are the criteria for choosing a phone with two SIM cards?

2 SIM or not 2 SIM?
First of all, you need to know that devices with two SIM cards are divided into two categories: Dual Standby and Active. They differ in the number of radio modules built into the device.

Dual Standby have one module that allows both SIM cards to be on the network. The subscriber will be available on both numbers, but only until he picks up one of them - when talking on one of the cards, it will become impossible to call the second. This increases the chances of missing an important call. Note, however, that after the conversation the second SIM card will appear on the network again, and a message from the operator will be sent to the phone about the missed call. Such popular devices as Nokia C2-00, Samsung Star II Duos C6712, and many Fly models (E170, Q300, Q410 and others) are built using Dual Standby technology.

Active is already two full-fledged phones in one body. This is because such devices have two separate radio modules (one for each SIM card). This provides the subscriber with a constant presence on the network on both numbers. Of course, such a system is more convenient. But we must take into account that phones with two active cards are often significantly more expensive. Samsung C5212 Duos, LG GX500 and some others have two radio modules.
Of course, there are also phones with old Standby technology, when cards are switched manually. But such devices are gradually leaving the market, becoming history.

Two SIM – double power consumption.

This statement applies more to devices with Active technology. Simultaneous operation of two radio modules significantly increases energy consumption. Therefore, we conclude: the battery capacity of a “dual-SIM” device is far from a minor factor.

Dual SIM smartphones.

A special caste of “two-SIM users” are smartphones with two cards. This area is not yet so numerous, but is growing rapidly. After all, one of the benefits of devices with two SIM cards is the ability to use one card for calls, and the second for working with the Internet. And for the latter, “smart phones” are much more interesting. Among the popular smartphones with two SIMs today, we note the ViewSonic V350, devices from the Gigabyte brand (GSmart S1205, Rola, others) and many Chinese clones of popular models.
Supports different networks.
Let us also remember that communication modules in phones with two SIM cards can provide connections in networks of different generations. More expensive devices often offer one standard GSM module, and a second one supporting 3G technology. This is again convenient for smartphones and for active work on the Internet.

Setting up a smartphone with two SIM cards.

How to set up a smartphone with two SIM cards.

Having a phone or smartphone with support for two SIM cards is very convenient and

profitable. Many mobile operators provide communication services between

subscribers of your network for free. What if your friends have different SIM cards?

operators, then you can talk to them for free using different SIM cards.

But in order to use this, your smartphone needs to have support for two SIM cards.

Don't forget that on the vast majority of smartphones the device can be active at the same time.

only one SIM card. That is, both SIM cards work for reception. But as soon as you start a conversation with

a subscriber using one SIM card, a subscriber who wants to call you on a second number,

will not be able to do this. He will be informed that you are busy or out of the service area. After graduation

conversation, you will see that you have a missed call, and you can call this person back.

To configure the operation of SIM cards, you need to do the following:

Insert two SIM cards into the smartphone, and in place of 1 SIM card you need to put your “main” SIM card (with the Internet, on which you will register Viber and WatsApp), although on some (newer) smartphones this is not necessary,

- turn on the smartphone,

- open “settings” by clicking the settings icon (or gear, or slider)

- open the “SIM cards” or “SIM card manager” section

- turn on the slides for SIM card No. 1 and SIM card No. 2 (move them so that they turn green)

- click on SIM card 1

In the table that appears, you can change the name of the SIM card (delete the old name and write a new one in the same way as you wrote the SMS), you can change the color of the contacts for this SIM card, write down the number of this SIM card, if you have such functions in your phone (I have such functions No)

- after making the changes, be sure to click the OK button at the bottom of the sign to save the changes.

- click on SIM card 2 and do the same procedure as with SIM card 1.

- click "Mobile data"

- select the SIM card with which we plan to use the Internet (on which tariff plan the Internet is cheaper, we choose that one), click on it (its name will be displayed)

- “Phone calls” and “SMS” click in the same way and select the “always ask” option both there and there.

- press the "BACK" button

- click on the item "Data transfer" ("mobile data")

- click on the inscription sim 1 at the top

- turn on the mobile data slider (move it)

- click on the inscription SIM 2 at the top

- turn off the mobile data slider (move it)

- if you take the Internet from SIM card 2, do the opposite

-on some smartphone models, mobile data can only be connected for both SIM cards at once, so we do that (enable it for both)

- press the "BACK" button

- click "MORE"

- click on "mobile networks"

- for the first SIM card (and then for the second, as we did before) select “network type”

- here I advise you to choose GSM, WCDMA, auto , for the SIM card from which we get the Internet, and only GSM for the second SIM card (because 3G or WCDMA can only be enabled for one SIM card, and on some smartphones, for example on Samsung, 3G can only be enabled for the first SIM card)

- on the desktop, look for and click the “Contacts” icon

- press the "all" button

- Click on the settings button (magic three dots)

- select "contact filter"

-if you don’t have such a function here, don’t despair, it can be hidden, for example here, like

in the figure below and your inscription will mean the place from where you are currently showing

contacts. It can be “phone memory”, SIM card No. 1, etc. Click on the inscription and it will open

window where the contact filter you are looking for will be.

-for example, on a Lenovo smartphone you need to press the menu button (to the left of the home button at the bottom of the screen)

and in the sign that appears, select “contact settings” and “contact filter”

- select which contacts will be displayed in your phone book, SIM 1, SIM 2, phone or others.

-if you don’t know (don’t remember) where you have which contacts are recorded, select “show all” or “all contacts”

I recommend choosing the “customize” option (or your own)

Here I advise you to select the contacts of your phone and both of your SIM cards (don’t forget to click “OK” each time to save the settings.

-and if you have a google account and your contacts are stored on its server, then select google contacts, how to do this look " "

- press the main screen button

If everything is done correctly, when you click on the “Contacts” icon in the “all” item, all your contacts should be displayed.

Now, to call someone, you need to click on the desired contact,

click on the number of one of the subscriber’s phone numbers (if there are several),

select the SIM card with which you will call him,

press the "call" icon

after this the connection with the subscriber will be started.

To end the conversation, click on the red button at the bottom of your screen.

Click on the picture to watch the video.

or look here

Updated 17 Sep 2019. Created 25 Dec 2017

You can’t force someone with no experience communicating with modern technology into the settings section of your smartphone. This approach sometimes leads to confusion, and a gadget that has not been told exactly how to behave begins to live its own life. One prominent example is a smartphone with two SIM cards, which people use together to optimize mobile communications costs. However, such optimization will be of no use if the smartphone does not receive precise instructions from you when and which SIM card to use.

It’s easier with calls and SMS: most smartphones, when you try to call or send a message, ask each time which SIM card number you need to use. The main thing here is to initially know your SIM cards in person and understand which one is the first and which is the second. As a last resort, this point can be clarified in the settings, in the “SIM Card Management” section.

There you can see which operator serves each card.

If the operator is the same, as in our example, you will have to deal with the numbers. Each operator has its own options for clarifying the number corresponding to the SIM card. In MTS, you can call the short number 0887 from the desired SIM card: the answering machine will dictate the number. This call is free.

Let's go online

On your smartphone with two SIM cards, the situation with mobile Internet is more complicated. If you open a social networking app or browser, your gadget, without asking you anything, simply connects to the Internet using the specified settings, and possibly through the wrong SIM card. This is why it is important to be able to change settings.

In the screenshot above, find the “Default data transfer” option. You see that data transfer (i.e. mobile Internet) is configured for the second SIM card. At the very top of the screenshot you can see that for each of the SIM cards the types of cellular networks that can be used are described. In particular, the first SIM card has access to any network, including the fastest, 4G. The second card is only “capable” of 2G, and therefore is only suitable for calls and extremely slow mobile Internet. Obviously, you should change the settings by switching the Internet to the first SIM card, like this:

We climb under the hood

There is an important nuance: the availability of modern cellular networks often depends not on the SIM card and the complete coverage of operator networks, but on how you place the SIM cards in your gadget. The fact is that in many phone models, only one of the two SIM card slots can provide connection to 3G and 4G networks. The second slot has limited functionality and is only compatible with 2G and calls. We took our screenshots from just such a smartphone.

If you mix up the slots and the SIM card for the mobile Internet is in the wrong place, you will have to swap the cards. In some smartphone models, during this procedure you will encounter another problem: sometimes the slots are designed for SIM cards of different sizes. To resolve this problem, the SIM card can be replaced while maintaining the number at the operator’s office, telling its employee what size card you need. As a rule, the SIM card replacement procedure will not cost you anything.

There are also adapters that allow you to install small cards in larger slots, and large cards can be cut using a special tool. You can almost always find it in a store that sells cell phones. Cutting a SIM card is usually a paid service.

As you can see, a dual-SIM smartphone gives you great convenience, but it can also have pitfalls. Now you know how to get around them.