OnePlus How to set calling SIM card to a contact

When using the dual SIM feature on the OnePlus smartphone, we can also assign a SIM card to the stored contacts, which is automatically dialed on each outgoing call without the device asking which number to use.

Note: For contacts that do not have assigned a SIM card, we are asked before the call and we can also set the default SIM for outgoing calls to the phone number directly.