Xiaomi
Set a Default Calling SIM for a Contact auf Xiaomi
Dual-SIM Xiaomi phones ask which card to use every time you call a contact, unless that contact has a fixed calling SIM stored in its profile. Without this setting, MIUI treats every outgoing call the same way and shows a manual SIM selection dialog before dialing.
Assigning a calling SIM to a contact removes that extra tap. Calls to that person always go out through the card you choose, for example a business line for work contacts or a cheaper rate plan for international numbers.
To set it, open Tap on Contacts ➔ Choose a Contact ➔ Open the Menu ➔ Tap on Set calling SIM ➔ Choose a SIM card (Dual SIM) and tap OK. The choice is saved per contact and applies only to voice calls from that contact entry.
This setting has no effect on messaging apps or mobile data routing, since those follow their own SIM preferences in the system settings. If a SIM slot is removed or disabled, the assigned card resets and MIUI falls back to asking manually again.