How to use two SIM cards on Galaxy S9 and S9+?

You can use two SIM cards on Galaxy S9 and S9+ if your phone is the dual-SIM version of Galaxy S9/S9+.

However, the dual-SIM version of Galaxy S9 and S9+ is dual standby only, not dual active. Therefore, you may encounter some limitations when you use two SIM cards in Galaxy S9 and S9+.

This Galaxy S9 guide answers all questions you may have on using two SIM cards on Galaxy S9 and S9+.

Is your Galaxy S9/S9+ capable of using two SIM cards?

Only the dual-SIM version Galaxy S9/S9+ can use two SIM cards. Don’t waste time or money to use two SIM cards if you got a single SIM version of Galaxy S9 or S9+.

If you bought your Galaxy S9 or S9+ in the US, very likely, it is a single SIM phone only. You cannot use two SIM cards on these phones sold in the US (through carriers and official distributors).

In most international markets, your Galaxy S9 or S9+ is very likely a dual-SIM version. And therefore, you may use up to two SIM cards on the phone.

You should always check with the seller on whether you can use two SIM cards on the phone you want to buy.

You can also check the Galaxy S9 box to see whether the Galaxy S9 or S9+ is dual SIM or single SIM version.

In most regions, the dual-SIM capability is usually marked as “duos” on the left side of the official Galaxy S9 box as shown below.

What are the limitations of using two SIM cards on Galaxy S9 and S9+?

The dual-SIM Galaxy S9  and S9+ are dual standby only, not dual active. This means both SIM cards are reachable when in the standby mode.

When you are talking through one SIM card,  the other SIM card, by default, will be unreachable unless you enable dual SIM always on.

For the explanation of the differences between dual standby and dual active dual SIM phones, you may check this guide.

The limitations of using two SIM cards on Galaxy S9 and S9+ include:

• When you are talking on one SIM card (through any mobile networks, 2G, 3G or 4G LTE), the other SIM card will be unreachable unless you enable dual SIM always on.
• When you pick up a voice call, the mobile data connection will be paused automatically.
• When you are talking on one SIM cards, you cannot use mobile data on the other SIM card.
• Although both SIM card slots support 4G LTE network, only one SIM card will connect to 4G LTE network at any time. The other SIM card will only connect to 3G 0r 2G network. By default, the SIM card assigned for mobile data will connect to 4G LTE.
• You need to explicitly assign one and only one SIM card for mobile data connection. By default, SIM card in the slot 1 will be used for data connection before you specify one.
• You cannot insert a micro SD card when you use two SIM cards in dual-SIM Galaxy S9 or S9+. The SIM card slot 2 in dual-SIM Galaxy S9 or S9+ can be used for a SIM card or a micro SD card, but not both at the same time as explained in this guide.
• Dual SIM always on, which requires call forwarding and call waiting (holding) may be not supported by a few carriers.

Please note, when you are using 3G or LTE mobile data on one SIM card, both SIM cards are reachable. It is the voice call that casue the avaialbility issues..

How to insert two SIM cards on dual-SIM Galaxy S9 and S9+?

As shown below, for the dual SIM Galaxy S9 and S9+, you have two options for using the SIM card slot.

If you want to use two SIM cards on Galaxy S9 and S9+, you have to choose option 1.

Of course, you can switch between two options at any time.

The bottom line is that you cannot put a SIM card AND a micro SD card in slot 2. You have to choose one of them at any given time.

Please refer to Galaxy S9 SIM card guide on how to insert SIM card into Galaxy S9 and S9+.

How to assign and manage default SIM cards for calls, messages and mobile data?

You can choose a default SIM card for outgoing calls and text messages when the app does not offer the option to select SIM cards.

Please note, the pre-installed Phone app and Messages app have separate buttons for each SIM card. But most third-party apps do not have such a feature and therefore may rely on default SIM card (preferred SIM card) settings.

In Galaxy S9 Settings, tap Connections, then tap SIM card manager as shown below.

SIM card manager is available on all dual-SIM version of Galaxy S9 and S9+. If you cannot find it under Settings– Connections, very likely, your Galaxy S9 or S9+ is the single SIM version and therefore only one SIM card be used.

In SIM card manager page, as shown above, you can set up preferred SIM card for calls, messages (SMS) and mobile data individually.

By default, SIM card 1 (the SIM card in slot 1) is used as the preferred (default) SIM card.

For example, you want to set the preferred SIM card for outgoing calls.

Tap Calls as shown above to set the default (preferred) SIM card for outgoing calls.

You can find the following 3 options for the preferred SIM card for outgoing calls:

• Ask always. You will be prompted to select a SIM card when necessary.
• SIM 1. The default (preferred) SIM card for outgoing calls is the one in slot 1.
• SIM 2. The default (preferred) SIM card for outgoing calls is the one in slot 2.

When you set the default SIM card for outgoing calls, you can find the icon in the status bar.

As explained in this guide, the icon will be different depending on your selection.

Similarly, you can set up the default SIM card for outgoing messages (SMS).

If you want to make both SIM cards reachable at all times,  you can enable Dual SIM always on (marked as 2) in the screenshot shown earlier.

Then you get a pop-up confirmation window:

Enable dual SIM always on? (With some service providers, this function may not work properly or you may be charged.

Tap OK as shown above to enable dual SIM always on.

How to customize SIM card icon, name and network type when using two SIM cards on Galaxy S9 or S9+?

To help you identify each SIM card, Galaxy S9 and S9+ allow you to customize the icon and name of two SIM cards used.

For example, you want to customize the SIM card icon, name and network type of SIM card 1.

Tap SIM 1 (marked as 3) in the SIM card manager page, as shown in the screenshot shown earlier.

In SIM card 1 page, as shown below, you can:

• Turn on or turn off SIM card 1 using the switch.
• Customize the SIM card icon.
• Customize the name of the SIM card.
• Customize the network type for SIM card 1.

To customize the icon for SIM card 1, tap Icon (marked as 4 in the screenshot below).

As shown above, you have 9 icon options for SIM card 1.

You can use any one of the icons except the one used by the other SIM card.

After you change the icon for the SIM cards, you can see the new icon in the notification panel and the status bar.

For example, as shown below, new SIM card icons were used for both SIM cards.

Of course, the status icon of the SIM cards in the status bar will be updated accordingly.

If you do not like the name “SIM 1” or “SIM 2”, you can name them as you want.

Tap Name (marked as 5) in SIM 1 page.

Then, as shown below, you can rename it to whatever you like.

By default, the SIM card assigned for mobile data will try to use 4G LTE network if available. The other SIM card will use 3G or 2G networks only.

So, whenever you change SIM card for mobile data, Galaxy S9 or S9+ will adjust the mobile network settings for the two SIM cards automatically.

If you want to change this behaviour, you can manually set the mobile network type.

In SIM 1 page, tap Network mode (marked as 6).

As shown above, you can set the network mode for SIM card 1:

• LTE/3G/2G  (auto).
• 3G/2G (auto).
• 3G only.
• 2G only.

For the explanations of the network mode (network type), you may check this guide.

Please note, only one SIM card can be set as LTE/3G/2G. The last setting will overwrite the existing settings.

How to choose the SIM card for outgoing calls and messages when using two SIM cards on Galaxy S9 or S9+?

If you are using the pre-installed Phone app and Messages app in Galaxy S9 and S9+, you can choose the SIM card for outgoing calls and messages when using two SIM cards.

As shown below, the Phone app (dialer) has two buttons for outgoing voice calls. One for SIM card 1, and the other for SIM card 2.

So, when you make voice calls, you can choose the SIM card on-the-fly.

Please note, these two buttons appear only after you inserted 2 SIM cards. Otherwise, there is only one button as in single SIM version of Galaxy S9 and S9+.

Also, you may notice there is only one video call button.

This means when you tap the vice call button in Galaxy S9 or S9+, the preferred (default) SIM card will be used. In this case, you cannot change the SIM card for video calls on the fly.

Similarly, in the pre-installed Messages app, there are two send buttons, as shown above, for SIM card 1 and SIM card 2 respectively.

If there is only one SIM card in Galaxy S9 or S9+, you will see only one button.

What is dual SIM always on when using two SIM cards on Galaxy S9 and S9+?

Because Galaxy S9 and S9+ dual-SIM are dual standby only, by default, when you are engaged in a call with one SIM card, the other SIM card will not be reachable.

You may lose some important calls in this case. This is one of the inherent limitations of dual SIM dual standby phones.

Galaxy S9 dual SIM always on allows you to make both SIM cards reachable at all times even when you are talking on one SIM card.  You will not miss any calls on both SIM cards.

In fact, dual SIM always on, when enabled, automatically set up the following 4 items for you:

• Call forwarding from SIM card 1 to card 2 when SIM card 1 is unreachable;
• Call forwarding from SIM card 2 to 1 when SIM card 2 is unreachable;
• Call waiting on SIM card 1;
• Call waiting on SIM card 2.

If any of your carriers do not support any of them, you will not be able to use dual SIM always on feature on Galaxy S9 and S9+.

Of course, you can manually set these 4 items on any dual standby Android phones as explained in this guide.

Please note,  when using dual SIM always on, you should consider following factors:

• You may be charged for both incoming and outgoing minutes for a forwarded call.
• If one SIM card is roaming, call forwarding may not work as expected.
• If one SIM card is roaming, the cost can be very high!

The call forwarding and call waiting features are offered by your carrier, not Galaxy S9 or S9+.  The settings are also saved on the SIM card, not on the phone.

Is the dual-SIM Galaxy S9/S9+ dual 4G?

No, Galaxy S9 and S9+ are 4G/3G/2g+3G/2G only.

So, you cannot connect both SIM cards to 4G LTE network concurrently, although both SIM cards can connect to 4G LTE.

Do you know how to use two SIM cards on Galaxy S9 and S9+ now?

If you have any questions or encounter any problems with using two SIM cards on Galaxy S9 and S9+, please let us know in the comment box below.

The community will help you find the answer

For the user guide for new features of Samsung Galaxy S9 and S9+, please check Galaxy S9 new features guides page.

For using Galaxy S9 and S9+, please check Galaxy S9 how-to guides page.

For using Galaxy S9 camera, please check Galaxy S9 camera guides page.

For accessories for Galaxy S9 and S9+, please check Galaxy S9 accessories guides page.

For the official Samsung Galaxy S9 and S9+ user guides (in PDF format), please check Galaxy S9 user guides page.