How to use two SIM cards in Galaxy S8 and S8+?

Dual SIM version Galaxy S8 and S8+ allows you to use two SIM cards in the phone. Although Galaxy S8 and S8+ are dual standby only, you can use dual SIM always on and will not miss any calls.

When you can use two SIM cards in Galaxy S8 and S8+?

For these dual SIM Galaxy S8 and S8+, you can use up to 2 SIM cards. Of course, they are dual standby only, not dual active because there is one modem shared by two SIM cards.

As explained in the Galaxy S8 SIM card guide, the SIM card tray for single SIM and dual SIM version of S8 and S8+ is different.

In addition, the metal contact part inside the phone is also different in dual SIM version and single SIM version of Galaxy S8 and S8+.

What are the limitations of using two SIM cards in Galaxy S8 and S8+?

This means you can receive and make calls on both SIM cards, but not concurrently.

However, you can set call forwarding from one SIM card to the other one, and enabling call waiting to get “dual SIM always on” (read on).

  • You cannot use micro SD card.
  • Dual standby only;
  • Only one SIM card can be assigned to use mobile data. By default, it is SIM card 1.
  • Most carriers will charge call forwarding minutes if you want to make both SIM cards available at any time even when you are engaged in a call.
  • Dual SIM always on may be not available in a few carriers’ networks who do not support call waiting (call holding).
  • Mobile data speed may be affected when using two SIM cards.
  • Battery life may be affected depending on signal strength and quality.

As explained in Galaxy S8 SIM card, you can put two SIM cards in the SIM card tray.

You just need follow the guide to put two SIM cards in the tray and they should be recognized after you power on your Galaxy S8 or S8+.

How to know whether you are using two SIM cards in Galaxy S8 and S8+?

For example, as shown below, you can find two signal strength bar (marked as 2 and 3 in the screenshot), instead of 1.

As shown below, when you use two SIM cards in Galaxy S8 and S8+,  under the quick settings bar, you can find the default SIM card info.

How to know whether you are using two SIM cards in Galaxy S8 and S8+?

You can customize SIM card settings for the two SIM cards in SettingsConnectionsSIM card manager.

If you want, you can just leave it as unknown. This should not affect any functions.

By default, SIM card 1 (in slot 1) is set as the preferred SIM card for all activities.

  • SIM 1; or
  • SIM 2; or
  • Always ask.
customize SIM card settings for two SIM cards in Galaxy S8 and S8+
customize SIM card settings for two SIM cards in Galaxy S8 and S8+

As shown below, you can tap the phone icon with number 1 to use SIM card 1, or phone icon with 2 to use SIM card 2, regardless of the SIM card preference settings.

Similarly, in call log (history tab), you can also choose SIM card to call back.

Under call settings as shown above, you can:

use two SIM cards in Galaxy S8 and S8+
use two SIM cards in Galaxy S8 and S8+

As mentioned earlier, dual SIM version of Galaxy S8 or S8+ is dual standby only.

This means you may miss some calls.

You just need to enable dual SIM always on (marked as 10).

  1. call waiting (call hold); and
  2. call forwarding (call diversion).

But call forwarding is not free. Your carrier will very likely charge it as the outgoing minutes.

When you enable dual SIM always on the first time, you will be asked to input the phone numbers of SIM card 1 and SIM card 2 as shown below.

After you provide the phone numbers, you can then choose to use dual SIM always on in 3 configurations:

The default option is both SIM cards.

dual sim always on: use two SIM cards in Galaxy S8 and S8+
dual sim always on: use two SIM cards in Galaxy S8 and S8+

Once you tap finish, Galaxy S8 and S8+ will write corresponding settings to each SIM card as shown above.

It also may take about 1 to 3 minutes to update the settings to SIM card.

Dual SIM always on

SIM card 2: SIM card 1 call waiting enabled. If SIM card 2 is out of reach, incoming calls will be forwarded to XXX (SIM card 1 number).

Tap OK to exit the settings.

How to check and fix problems related to using dual SIM cards in Galaxy S8 and S8+?

In SettingsAbout phone, tap status as shown below.

check and fix problems related to using dual SIM cards in Galaxy S8 and S8+
check and fix problems related to using dual SIM cards in Galaxy S8 and S8+

In SIM card status page, you can find two tabs: one for SIM 1 and the other for SIM 2.

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