We can set default SIM for contacts while calling on dual sim androids. But how if your device automatically selects the SIM to call with for your specific contacts.
Although the android API doesn't provide to develop apps for Duel SIM interface but this app manages to automatically select the predefined SIM for your contacts.
Just go to interface, add some sample with the contacts's complete number, select the default SIM for it and if necessary go to Options and select the System option and change the way to call. Mode 1 works fine for me.
Google Play Link
The app is free. Use it and don't forget to Rate it in Play Store
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