Software i OxygenOS
Just go to
SETTINGS - SIM CARDS
Under
preferred SIM for:
Mobile Data: Yours choice
Calls: Yours choice of standard sim cards or let it ask every time you have to call somebody
SMS Messages: Yours choise of standard sim card or let it ask you every time
You can also give the sim cards names of yours choice - Mine is named PRIVATE and WORK. Then you recieve a phonecall you can see of the notofication which sim card they are trying to reach you on.
My own settings:
Mobile data: Private sim card (I can use around 20 GB per month)
Calls: Ask me every time (because my second sim card is work related)
It works like.... Then I want to call somebody, it ask my which sim card I want to use

SMS: Private sim card (I have free messages)
Click to expand...