Almost all the android smartphones come with Dual SIM support. We can set the default SIM selection according to our preference for Call and Message in the settings. Here we are going into the details of default sim selection for dual sim android phones, and let us follow the steps.

Steps 1: Go to the phone settings.

Step 2: Select SIM Card settings.
Screen 1

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Step 3: In the new page click on Message or Call settings
Screen 2

Steps 4: Click on the Sending message option or call option to select the sim

Step 5: In the Popup 3 options will be available, always use SIM 1, Always use SIM 2 and Ask every time,
Screen 3

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Set your preference accordingly; if you choose the 3rd option, each time you send a message or make a call, it will ask you which SIM card to use. Do the same steps for Call settings also so that the dual sim phones can have the default selection.